3-substituted-2(arylalkyl)-1-azabicycloalkanes and methods of use thereof

ABSTRACT

The present invention relates to 3-substituted-2-(arylalkyl)-1-azabicycloalkanes, methods of preparing the compounds and methods of treatment using the compounds. The compounds exhibit activity at nicotinic acetylcholine receptors (nAChRs), particularly the α7 nAChR subtype, and are useful towards modulating neurotransmission and the release of ligands involved in neurotransmission. Methods for preventing or treating conditions and disorders, including central nervous system (CNS) disorders, which are characterized by an alteration in normal neurotransmission, are also disclosed. Also disclosed are methods for treating inflammation, autoimmune disorders, pain and excess neovascularization, such as that associated with tumor growth.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 11/157,119 , filedJun. 20, 2005, now U.S. Pat. No. 7,767,193, which is a continuation ofU.S. Ser. No. 10/372,642, filed on Feb. 21, 2003, now U.S. Pat. No.6,953,855, each of which is incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to pharmaceutical compositionsincorporating compounds capable of affecting nicotinic acetylcholinergicreceptors (nAChRs), for example, as modulators of specific nicotinicreceptor subtypes (specifically, the α7 nAChR subtype). The presentinvention also relates to methods for treating a wide variety ofconditions and disorders, particularly those associated with dysfunctionof the central and autonomic nervous systems.

BACKGROUND OF THE INVENTION

Nicotine has been proposed to have a number of pharmacological effects.See, for example, Pullan et al., N. Engl. J. Med. 330:811 (1994).Certain of those effects may be related to effects upon neurotransmitterrelease. See, for example, Sjak-shie et al., Brain Res. 624:295 (1993),where neuroprotective effects of nicotine are proposed. Release ofacetylcholine and dopamine by neurons, upon administration of nicotine,has been reported by Rowell et al., J. Neurochem. 43:1593 (1984); Rapieret al., J. Neurochem. 50:1123 (1988); Sandor et al., Brain Res. 567:313(1991) and Vizi, Br. J. Pharmacol. 47:765 (1973). Release ofnorepinephrine by neurons, upon administration of nicotine, has beenreported by Hall et al., Biochem. Pharmacol. 21:1829 (1972). Release ofserotonin by neurons, upon administration of nicotine, has been reportedby Hery et al., Arch. Int. Pharmacodyn. Ther. 296:91 (1977). Release ofglutamate by neurons, upon administration of nicotine, has been reportedby Toth et al., Neurochem Res. 17:265 (1992). Confirmatory reports andadditional recent studies have included the modulation, in the centralnervous system (CNS), of glutamate, nitric oxide, GABA, tachykinins,cytokines, and peptides (reviewed in Brioni et al., Adv. Pharmacol.37:153 (1997)). In addition, nicotine reportedly potentiates thepharmacological behavior of certain pharmaceutical compositions used forthe treatment of certain disorders. See, for example, Sanberg et al.,Pharmacol. Biochem. & Behavior 46:303 (1993); Harsing et al., J.Neurochem. 59:48 (1993) and Hughes, Proceedings from Intl. Symp. Nic.S40 (1994). Furthermore, various other beneficial pharmacologicaleffects of nicotine have been proposed. See, for example, Decina et al.,Biol. Psychiatry 28:502 (1990); Wagner et al., Pharmacopsychiatry 21:301(1988); Pomerleau et al., Addictive Behaviors 9:265 (1984); Onaivi etal., Life Sci. 54(3):193 (1994); Tripathi et al., JPET 221:91 (1982) andHamon, Trends in Pharmacol. Res. 15:36 (1994).

Various compounds that target nAChRs have been reported as being usefulfor treating a wide variety of conditions and disorders. See, forexample, Williams et al., DN&P 7(4):205 (1994); Arneric et al., CNS DrugRev. 1(1):1 (1995); Arneric et al., Exp. Opin. Invest. Drugs 5(1):79(1996); Bencherif et al., JPET 279:1413 (1996); Lippiello et al., JPET279:1422 (1996); Damaj et al., J. Pharmacol. Exp. Ther. 291:390 (1999);Chiari et al., Anesthesiology 91:1447 (1999); Lavand'homme andEisenbach, Anesthesiology 91:1455 (1999); Holladay et al., J. Med. Chem.40(28): 4169 (1997); Bannon et al., Science 279: 77 (1998); PCT WO94/08992, PCT WO 96/31475, PCT WO 96/40682, and U.S. Pat. No. 5,583,140to Bencherif et al., U.S. Pat. No. 5,597,919 to Dull et al., U.S. Pat.No. 5,604,231 to Smith et al., and U.S. Pat. No. 5,852,041 to Cosford etal. Nicotinic compounds are reported as being particularly useful fortreating a wide variety of CNS disorders. Indeed, a wide variety ofcompounds have been reported to have therapeutic properties. See, forexample, Bencherif and Schmitt, Current Drug Targets: CNS andNeurological Disorders 1(4): 349 (2002), Levin and Rezvani, Current DrugTargets: CNS and Neurological Disorders 1(4): 423 (2002), O'Neill etal., Current Drug Targets: CNS and Neurological Disorders 1(4): 399(2002), U.S. Pat. No. 5,1871,166 to Kikuchi et al., U.S. Pat. No.5,672,601 to Cignarella, PCT WO 99/21834, and PCT WO 97/40049, UK PatentApplication GB 2295387, and European Patent Application 297,858.

CNS disorders are a type of neurological disorder. CNS disorders can bedrug induced; can be attributed to genetic predisposition, infection ortrauma; or can be of unknown etiology. CNS disorders compriseneuropsychiatric disorders, neurological diseases and mental illnesses,and include neurodegenerative diseases, behavioral disorders, cognitivedisorders and cognitive affective disorders. There are several CNSdisorders whose clinical manifestations have been attributed to CNSdysfunction (i.e., disorders resulting from inappropriate levels ofneurotransmitter release, inappropriate properties of neurotransmitterreceptors, and/or inappropriate interaction between neurotransmittersand neurotransmitter receptors). Several CNS disorders can be attributedto a deficiency of choline, dopamine, norepinephrine and/or serotonin.Relatively common CNS disorders include pre-senile dementia (early-onsetAlzheimer's disease), senile dementia (dementia of the Alzheimer'stype), micro-infarct dementia, AIDS-related dementia, Creutzfeld-Jakobdisease, Pick's disease, Parkinsonism including Parkinson's disease,Lewy body dementia, progressive supranuclear palsy, Huntington's chorea,tardive dyskinesia, hyperkinesia, mania, attention deficit disorder,anxiety, dyslexia, schizophrenia, depression, obsessive-compulsivedisorders and Tourette's syndrome.

The nAChRs characteristic of the CNS have been shown to occur in severalsubtypes, the most common of which are the α4β2 and α7 subtypes. See,for example, Schmitt, Current Med. Chem. 7: 749 (2000). Ligands thatinteract with the α7 nAChR subtype have been proposed to be useful inthe treatment of schizophrenia. There are a decreased number ofhippocampal nAChRs in postmortem brain tissue of schizophrenic patients.Also, there is improved psychological effect in smoking versusnon-smoking schizophrenic patients. Nicotine improves sensory gatingdeficits in animals and schizophrenics. Blockade of the α7 nAChR subtypeinduces a gating deficit similar to that seen in schizophrenia. See, forexample, Leonard et al., Schizophrenia Bulletin 22(3): 431 (1996).Biochemical, molecular, and genetic studies of sensory processing, inpatients with the P50 auditory-evoked potential gating deficit, suggestthat the α7 nAChR subtype may function in an inhibitory neuronalpathway. See, for example, Freedman et al., Biological Psychiatry38(1):22 (1995).

More recently, α7 nAChRs have been proposed to be mediators ofangiogenesis, as described by Heeschen et al., J. Clin. Invest. 100: 527(2002). In these studies, inhibition of the α7 subtype was shown todecrease inflammatory angiogenesis. Also, α7 nAChRs have been proposedas targets for controlling neurogenesis and tumor growth (Utsugisawa etal., Molecular Brain Research 106(1-2): 88 (2002) and U.S. PatentApplication 2002/0016371). Finally, the role of the α7 subtype incognition (Levin and Rezvani, Current Drug Targets: CNS and NeurologicalDisorders 1(4): 423 (2002)), neuroprotection (O'Neill et al., CurrentDrug Targets: CNS and Neurological Disorders 1(4): 399 (2002) andJeyarasasingam at al., Neuroscience 109(2): 275 (2002)), and neuropathicpain (Xiao et al., Proc. Nat. Acad. Sci. (US) 99(12): 8360 (2002)) hasrecently been recognized.

Various compounds have been reported to interact with α7 nAChRs and havebeen proposed as therapies on that basis. See, for instance, PCT WO99/62505, PCT WO 99/03859, PCT WO 97/30998, PCT WO 01/36417, PCT WO02/15662, PCT WO 02/16355, PCT WO 02/16356, PCT WO 02/16357, PCT WO02/16358, PCT WO 02/17358, Stevens et al., Psychopharm. 136: 320 (1998),Dolle et al., J. Labelled Comp. Radiopharm. 44: 785 (2001) and Macor etal., Bioorg. Med. Chem. Lett. 11: 319 (2001) and references therein.Among these compounds, a common structural theme is that of thesubstituted tertiary bicylic amine (e.g., quinuclidine). Similarsubstituted quinuclidine compounds have also been reported to bind atmuscarinic receptors. See, for instance, U.S. Pat. No. 5,712,270 to Sabband PCTs WO 02/00652 and WO 02/051841.

It would be desirable to provide a useful method for the prevention andtreatment of a condition or disorder by administering a nicotiniccompound to a patient susceptible to or suffering from such a conditionor disorder. It would be highly beneficial to provide individualssuffering from certain disorders (e.g., CNS diseases) with interruptionof the symptoms of those disorders by the administration of apharmaceutical composition containing an active ingredient havingnicotinic pharmacology which has a beneficial effect (e.g., upon thefunctioning of the CNS), but does not provide any significant associatedside effects. It would be highly desirable to provide a pharmaceuticalcomposition incorporating a compound that interacts with nAChRs, such asthose that have the potential to affect the functioning of the CNS. Itwould be highly desirable that such a compound, when employed in anamount sufficient to affect the functioning of the CNS, would notsignificantly affect those nAChR subtypes that have the potential toinduce undesirable side effects (e.g., appreciable activity atcardiovascular and skeletal muscle receptor sites). In addition, itwould be highly desirable to provide a pharmaceutical compositionincorporating a compound which interacts with nicotinic receptors butnot muscarinic receptors, as the latter are associated with sideeffects, such as hypersalivation, sweating, tremors, cardiovascular andgastrointestinal disturbances, related to the function of theparasympathetic nervous system (see Caulfield, Pharmacol. Ther. 58: 319(1993) and Broadley and Kelly, Molecules 6: 142 (2001)). Furthermore, itwould be highly desirable to provide pharmaceutical compositions, whichare selective for the α7 nAChR subtype, for the treatment of certainconditions or disorders (e.g., schizophrenia, cognitive disorders, andneuropathic pain) and for the prevention of tissue damage and thehastening of healing (i.e., for neuroprotection and the control ofangiogenesis). The present invention provides such compounds,compositions and methods.

SUMMARY OF THE INVENTION

The present invention relates to3-substituted-2-(arylalkyl)-1-azabicycloalkanes, pharmaceuticalcompositions including the compounds, methods of preparing thecompounds, and methods of treatment using the compounds. Morespecifically, the methods of treatment involve modulating the activityof the α7 nAChR subtype by administering one or more of the compounds totreat or prevent disorders mediated by the α7 nAChR subtype.

The azabicycloalkanes generally are azabicycloheptanes,azabicyclooctanes, or azabicyclononanes. The aryl group in the arylalkylmoiety is a 5- or 6-membered ring heteroaromatic, preferably 3-pyridinyland 5-pyrimidinyl moieties, and the alkyl group is typically a C₁₋₄alkyl. The substituent at the 3-position of the 1-azabicycloalkane is acarbonyl-containing functional group, such as an amide, carbamate, urea,thioamide, thiocarbamate, thiourea or similar functionality.

The compounds are beneficial in therapeutic applications requiring aselective interaction at certain nAChR subtypes. That is, the compoundsmodulate the activity of certain nAChR subtypes, particularly the α7nAChR subtype, and do not have appreciable activity toward muscarinicreceptors. The compounds can be administered in amounts sufficient toaffect the functioning of the central nervous system (CNS) withoutsignificantly affecting those receptor subtypes that have the potentialto induce undesirable side effects (e.g., without appreciable activityat ganglionic and skeletal muscle nAChR sites and at muscarinicreceptors). The compounds are therefore useful towards modulatingrelease of ligands involved in neurotransmission, without appreciableside effects.

The compounds can be used as therapeutic agents to treat and/or preventdisorders characterized by an alteration in normal neurotransmitterrelease. Examples of such disorders include certain CNS conditions anddisorders. The compounds can provide neuroprotection, treat patientssusceptible to convulsions, treat depression, autism, and certainneuroendocrine disorders, and help manage stroke patients. The compoundsalso are useful in treating hypertension, type II diabetes and neoplasiaand effecting weight loss. As the compounds are selective for the α7nAChR subtype, they can be used to treat certain conditions or disorders(e.g., schizophrenia, cognitive disorders, and neuropathic pain),prevent tissue damage, and hasten healing (i.e., provide neuroprotectionand control of angiogenesis).

The pharmaceutical compositions provide therapeutic benefit toindividuals suffering from such conditions or disorders and exhibitingclinical manifestations of such conditions or disorders. The compounds,administered with the pharmaceutical compositions, can be employed ineffective amounts to (i) exhibit nicotinic pharmacology and affectrelevant nAChR sites (e.g., act as a pharmacological agonists atnicotinic receptors), and (ii) modulate neurotransmitter secretion, andhence prevent and suppress the symptoms associated with those diseases.In addition, the compounds have the potential to (i) increase the numberof nAChRs of the brain of the patient, (ii) exhibit neuroprotectiveeffects and (iii) when employed in effective amounts, not causeappreciable adverse side effects (e.g., significant increases in bloodpressure and heart rate, significant negative effects upon thegastro-intestinal tract, and significant effects upon skeletal muscle).The pharmaceutical compositions are believed to be safe and effectivewith regards to prevention and treatment of various conditions ordisorders.

The foregoing and other aspects of the present invention are explainedin detail in the detailed description and examples set forth below.

DETAILED DESCRIPTION OF THE INVENTION

The compounds described herein have structures that are represented byFormulas 1 and 2.

In Formulas 1 and 2, m and n individually can have a value of 1 or 2,and p can have a value of 1, 2, 3 or 4. In the Formulas, X is eitheroxygen or nitrogen (i.e., NR′), Y is either oxygen or sulfur, and Z iseither nitrogen (i.e., NR′), a covalent bond or a linker species, A. Ais selected from the group —CR′R″—, —CR′R″—CR′R″—, —CR′═CR′—, and —C₂—,wherein R′ and R″ are as hereinafter defined. When Z is a covalent bondor A, X must be nitrogen. Ar is an aryl group, either carbocyclic orheterocyclic, either monocyclic or fused polycyclic, unsubstituted orsubstituted; and Cy is a 5- or 6-membered heteroaromatic ring,unsubstituted or substituted. The wavy lines indicate that both relativeand absolute stereochemistry at those sites are variable (e.g., cis ortrans, R or S). The invention further includes pharmaceuticallyacceptable salts thereof. The compounds have one or more asymmetriccarbons and can therefore exist in the form of racemic mixtures,enantiomers and diastereomers. In addition, some of the compounds existas E and Z isomers about a carbon-carbon double bond. All theseindividual isomeric compounds and their mixtures are also intended to bewithin the scope of the present invention.

Thus, the invention includes compounds in which Ar is linked to theazabicycle by a carbonyl group-containing functionality, such as anamide, carbamate, urea, thioamide, thiocarbamate or thioureafunctionality. In addition, in the case of the amide and thioamidefunctionalities, Ar may be bonded directly to the carbonyl (orthiocarbonyl) group or may be linked to the carbonyl (or thiocarbonyl)group through linker A. Furthermore, the invention includes compoundsthat contain a 1-azabicycle, containing either a 5-, 6-, or 7-memberedring and having a total of 7, 8 or 9 ring atoms (e.g.,1-azabicyclo[2.2.1]heptane, 1-azabicyclo[3.2.1]octane,1-azabicyclo[2.2.2]octane, and 1-azabicyclo[3.2.2]nonane).

As used herein, “alkoxy” includes alkyl groups from 1 to 8 carbon atomsin a straight or branched chain, also C₃₋₈ cycloalkyl, bonded to anoxygen atom.

As used herein, “alkyl” includes straight chain and branched C₁₋₈ alkyl,preferably C₁₋₆ alkyl. “Substituted alkyl” defines alkyl substituentswith 1-3 substituents as defined below in connection with Ar and Cy.

As used herein, “arylalkyl” refers to moieties, such as benzyl, whereinan aromatic is linked to an alkyl group which is linked to the indicatedposition in the compound of Formulas 1 or 2. “Substituted arylalkyl”defines arylalkyl substituents with 1-3 substituents as defined below inconnection with Ar and Cy.

As used herein, “aromatic” refers to 3- to 10-membered, preferably 5-and 6-membered, aromatic and heteroaromatic rings and polycyclicaromatics including 5- and/or 6-membered aromatic and/or heteroaromaticrings.

As used herein, “aryl” includes both carbocyclic and heterocyclicaromatic rings, both monocyclic and fused polycyclic, where the aromaticrings can be 5- or 6-membered rings. Representative monocyclic arylgroups include, but are not limited to, phenyl, furanyl, pyrrolyl,thienyl, pyridinyl, pyrimidinyl, oxazolyl, isoxazolyl, pyrazolyl,imidazolyl, thiazolyl, isothiazolyl and the like. Fused polycyclic arylgroups are those aromatic groups that include a 5- or 6-memberedaromatic or heteroaromatic ring as one or more rings in a fused ringsystem. Representative fused polycyclic aryl groups include naphthalene,anthracene, indolizine, indole, isoindole, benzofuran, benzothiophene,indazole, benzimidazole, benzthiazole, purine, quinoline, isoquinoline,cinnoline, phthalazine, quinazoline, quinoxaline, 1,8-naphthyridine,pteridine, carbazole, acridine, phenazine, phenothiazine, phenoxazine,and azulene.

As used herein, a “carbonyl group-containing moiety” is a moiety of theformula —X—C(═Y)—Z—Ar, where X, C, Y, Z and Ar are as defined herein.

As used herein, “Cy” groups are 5- and 6-membered ring heteroaromaticgroups. Representative Cy groups include pyridinyl, pyrimidinyl,furanyl, pyrrolyl, thienyl, oxazolyl, isoxazolyl, pyrazolyl, imidazolyl,thiazolyl, isothiazolyl and the like.

Individually, Ar and Cy can be unsubstituted or can be substituted with1, 2 or 3 substituents, such as alkyl, alkenyl, heterocyclyl,cycloalkyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl,halo (e.g., F, Cl, Br, or I), —OR′, —NR′R″, —CF₃, —CN, —NO₂, —C₂R′,—SR′, —N₃, —C(═O)NR′R″, —NR′C(═O)R″, —C(═O)R′, —C(═O)OR′, —OC(═O)R′,—O(CR′R″)_(r)C(═O)R′, —O(CR′R″)_(r)NR″C(═O)R′, —O(CR′R″)_(r)NR″SO₂R′,—OC(═O)NR′R″, —NR′C(═O)O R″, —SO₂R′, —SO₂NR′R″, and —NR′SO₂R″, where R′and R″ are individually hydrogen, lower alkyl (e.g., straight chain orbranched alkyl including C₁-C₈, preferably C₁-C₅, such as methyl, ethyl,or isopropyl), cycloalkyl, heterocyclyl, aryl, or arylalkyl (such asbenzyl), and r is an integer from 1 to 6. R′ and R″ can also combine toform a cyclic functionality.

As used herein, cycloalkyl radicals contain from 3 to 8 carbon atoms.Examples of suitable cycloalkyl radicals include, but are not limitedto, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl andcyclooctyl. As used herein, polycycloalkyl radicals are selected fromadamantyl, bornanyl, norbornanyl, bornenyl and norbornenyl.

As used herein, halogen is chlorine, iodine, fluorine or bromine.

As used herein, heteroaryl radicals are rings that contain from 3 to 10members, preferably 5 or 6 members, including one or more heteroatomsselected from oxygen, sulphur and nitrogen. Examples of suitable5-membered ring heteroaryl moieties include furyl, pyrrolyl, imidazolyl,oxazolyl, thiazolyl, thienyl, tetrazolyl, and pyrazolyl. Examples ofsuitable 6-membered ring heteroaryl moieties include pyridinyl,pyrimidinyl, pyrazinyl, of which pyridinyl and pyrimidinyl arepreferred.

As used herein, “heterocyclic” or “heterocyclyl” radicals include ringswith 3 to 10 members, including one or more heteroatoms selected fromoxygen, sulphur and nitrogen. Examples of suitable heterocyclic moietiesinclude, but are not limited to, piperidinyl, morpholinyl, pyrrolidinyl,imidazolidinyl, pyrazolidinyl, isothiazolidinyl, thiazolidinyl,isoxazolidinyl, oxazolidinyl, piperazinyl, tetrahydropyranyl andtetrahydrofuranyl.

Examples of suitable pharmaceutically acceptable salts include inorganicacid addition salts such as chloride, bromide, sulfate, phosphate, andnitrate; organic acid addition salts such as acetate, galactarate,propionate, succinate, lactate, glycolate, malate, tartrate, citrate,maleate, fumarate, methanesulfonate, p-toluenesulfonate, and ascorbate;salts with acidic amino acid such as aspartate and glutamate; alkalimetal salts such as sodium salt and potassium salt; alkaline earth metalsalts such as magnesium salt and calcium salt; ammonium salt; organicbasic salts such as trimethylamine salt, triethylamine salt, pyridinesalt, picoline salt, dicyclohexylamine salt, andN,N′-dibenzylethylenediamine salt; and salts with basic amino acid suchas lysine salt and arginine salt. The salts may be in some caseshydrates or ethanol solvates. Representative salts are provided asdescribed in U.S. Pat. No. 5,597,919 to Dull et al., U.S. Pat. No.5,616,716 to Dull et al. and U.S. Pat. No. 5,663,356 to Ruecroft et al.

As used herein, neurotransmitters whose release is modulated (i.e.,increased or decreased, depending on whether the compounds function asagonists, partial agonists or antagonists) by the compounds describedherein include, but are not limited to, acetylcholine, dopamine,norepinephrine, serotonin and glutamate, and the compounds describedherein function as modulators of one or more nicotinic receptors.

As used herein, an “agonist” is a substance that stimulates its bindingpartner, typically a receptor. Stimulation is defined in the context ofthe particular assay, or may be apparent in the literature from adiscussion herein that makes a comparison to a factor or substance thatis accepted as an “agonist” or an “antagonist” of the particular bindingpartner under substantially similar circumstances as appreciated bythose of skill in the art. Stimulation may be defined with respect to anincrease in a particular effect or function that is induced byinteraction of the agonist or partial agonist with a binding partner andcan include allosteric effects.

As used herein, an “antagonist” is a substance that inhibits its bindingpartner, typically a receptor. Inhibition is defined in the context ofthe particular assay, or may be apparent in the literature from adiscussion herein that makes a comparison to a factor or substance thatis accepted as an “agonist” or an “antagonist” of the particular bindingpartner under substantially similar circumstances as appreciated bythose of skill in the art. Inhibition may be defined with respect to andecrease in a particular effect or function that is induced byinteraction of the antagonist with a binding partner, and can includeallosteric effects.

As used herein, a “partial agonist” is a substance that provides a levelof stimulation to its binding partner that is intermediate between thatof a full or complete antagonist and an agonist defined by any acceptedstandard for agonist activity. It will be recognized that stimulation,and hence, inhibition is defined intrinsically for any substance orcategory of substances to be defined as agonists, antagonists, orpartial agonists. As used herein, “intrinsic activity”, or “efficacy,”relates to some measure of biological effectiveness of the bindingpartner complex. With regard to receptor pharmacology, the context inwhich intrinsic activity or efficacy should be defined will depend onthe context of the binding partner (e.g., receptor/ligand) complex andthe consideration of an activity relevant to a particular biologicaloutcome. For example, in some circumstances, intrinsic activity may varydepending on the particular second messenger system involved. See Hoyer,D. and Boddeke, H., Trends Pharmacol Sci. 14(7):270-5 (1993). Where suchcontextually specific evaluations are relevant, and how they might berelevant in the context of the present invention, will be apparent toone of ordinary skill in the art.

In one embodiment, the value of p is 1, Cy is 3-pyridinyl or5-pyrimidinyl, X and Y are oxygen, Z is nitrogen and the relativestereochemistry of the substituents in the 2 and 3 positions of theazabicycle is cis. In another embodiment, the value of p is 1, Cy is3-pyridinyl or 5-pyrimidinyl, X and Z are nitrogen, Y is oxygen, and therelative stereochemistry of the substituents in the 2 and 3 positions ofthe azabicycle is cis. In a third embodiment, the value of p is 1, Cy is3-pyridinyl or 5-pyrimidinyl, X is nitrogen, Y is oxygen, Z is acovalent bond (between the carbonyl and Ar) and the relativestereochemistry of the substituents in the 2 and 3 positions of theazabicycle is cis. In a fourth embodiment, the value of p is 1, Cy is3-pyridinyl or 5-pyrimidinyl, X is nitrogen, Y is oxygen, Z is A (alinker species between the carbonyl and Ar) and the relativestereochemistry of the substituents in the 2 and 3 positions of theazabicycle is cis.

Representative compounds of the present invention include:

-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-phenylcarbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-fluorophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-chlorophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-bromophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-fluorophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-chlorophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-bromophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-fluorophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-chlorophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-bromophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3,4-dichlorophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-methylphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-biphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-methylphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-biphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-methylphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-biphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-cyanophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-cyanophenyl)carbamate,-   (R, R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-cyanophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-trifluoromethylphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-dimethylaminophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-methoxyphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-phenoxyphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-methylthiophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-phenylthiophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-methoxyphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-phenoxyphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-methylthiophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-phenylthiophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-methoxyphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-phenoxyphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-methylthiophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(4-phenylthiophenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2,4-dimethoxyphenyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-thienyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-thienyl)carbamate,-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(3-benzothienyl)carbamate,-   (R, R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(1-naphthyl)carbamate, and-   (R,R; R,S; S,R; and    S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl    N-(2-naphthyl)carbamate.

Other compounds representative of the present invention include:

-   (R,R; R,S; S,R; and    S,S)—N-phenyl-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-fluorophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-chlorophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-bromophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-fluorophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-chlorophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-bromophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-fluorophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-chlorophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-bromophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3,4-dichlorophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-methylphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-biphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-methylphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-biphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-methylphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-biphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-cyanophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-cyanophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-cyanophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-trifluoromethylphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-dimethylaminophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-methoxyphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-phenoxyphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-methylthiophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-phenylthiophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-methoxyphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-phenoxyphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-methylthiophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-phenylthiophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-methoxyphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-phenoxyphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-methylthiophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(4-phenylthiophenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2,4-dimethoxyphenyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(2-thienyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-thienyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(3-benzothienyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,-   (R,R; R,S; S,R; and    S,S)—N-(1-naphthyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea,    and-   (R,R; R,S; S,R; and    S,S)—N-(2-naphthyl)-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea.

Other compounds representative of the present invention include:

-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-fluorobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-fluorobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-fluorobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-chlorobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-chlorobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-chlorobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-bromobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-bromobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-bromobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3,4-dichlorobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-methylbenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-methylbenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-methylbenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-phenylbenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-phenylbenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-phenylbenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-cyanobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-cyanobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-cyanobenzamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-trifluoromethylbenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-dimethylaminobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-methoxybenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-methoxybenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-methoxybenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-phenoxybenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-phenoxybenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-phenoxybenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-methylthiobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-methylthiobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-methylthiobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-phenylthiobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-phenylthiobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-phenylthiobenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2,4-dimethoxybenzamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-bromonicotinamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-6-chloronicotinamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-phenylnicotinamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)furan-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)furan-3-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)thiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-bromothiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-methylthiothiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-phenylthiothiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-methylthiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-methylthiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-bromothiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-chlorothiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-(2-pyridinyl)thiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-5-acetylthiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-ethoxythiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-methoxythiophene-2-carboxamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-acetyl-3-methyl-5-methylthiothiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)thiophene-3-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-1-methylpyrrole-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)pyrrole-3-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)indole-2-carboxamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)indole-3-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-1-methylindole-3-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-1-benzylindole-3-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-1H-benzimidazole-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-1-isopropyl-2-trifluoromethyl-1H-benzimidazole-5-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-1-isopropyl-1H-benzotriazole-5-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzo[b]thiophene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzo[b]thiophene-3-carboxamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-3-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-3-methylbenzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-5-nitrobenzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-5-methoxybenzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-7-methoxybenzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-7-ethoxybenzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-3-methyl-5-chlorobenzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-6-bromobenzofuran-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-4-acetyl-7-methoxybenzofuran-2-carboxamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-2-methylbenzofuran-4-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)naphtho[2,1-b]furan-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)naphthalene-1-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)naphthalene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-6-aminonaphthalene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-3-methoxynaphthalene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-6-methoxynaphthalene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-1-hydroxynaphthalene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-6-hydroxynaphthalene-2-carboxamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)-6-acetoxynaphthalene-2-carboxamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)3-phenylprop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-fluorophenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-methoxyphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-methyl-3-phenylprop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(2-fluorophenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-methylphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-fluorophenyl)prop-2-enamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-methylphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(2-furyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(2-methoxyphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-bromophenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-methoxyphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-hydroxyphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-bromophenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-chlorophenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-hydroxyphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-hydroxy-3-methoxyphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(2-thienyl)prop-2-enamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-pyridinyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-biphenyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(1-naphthyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-thienyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-isopropylphenyl)prop-2-enamide,-   (R, R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-methyl-3-phenylprop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-furyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-2-ethyl-3-phenylprop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(2-pyridinyl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3,4-dimethylthieno[2,3-b]thiophen-2-yl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(3-methylthien-2-yl)prop-2-enamide,-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(2-naphthyl)prop-2-enamide,    and-   (R,R; R,S; S,R; and    S,S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-3-(4-methylthiophenyl)prop-2-enamide.

Compounds resulting from substitution of NCH₃ for NH, in any of thecarbonyl group-containing moieties in the foregoing representativecompounds, are also representative compounds of the present invention.Compounds resulting from the substitution of 1-azabicyclo[2.2.2]octane,in any of the forgoing representative compounds, with either1-azabicyclo[2.2.1]heptane, 1-azabicyclo[3.2.1]octane or1-azabicyclo[3.2.2]nonane are also representative compounds of thepresent invention.

More specifically, the compounds of Formula 2 include compounds of thefollowing general formulas:

In each of these compounds, individual isomers thereof, mixturesthereof, including racemic mixtures, enantiomers, diastereomers andtautomers thereof, and the pharmaceutically acceptable salts thereof,are intended to be within the scope of the present invention.

I. Methods of Preparing the Compounds

Preparation of 2-(Arylalkyl)-1-azabicycloalkanes

Compounds of Formulas 1 and 2 are 3-substituted2-(arylalkyl)-1-azabicycloalkanes. While the manner in which compoundsof the present invention can be prepared can vary, they are convenientlyprepared using intermediates (ketones and alcohols) generated during thesynthesis of 2-(arylalkyl)-1-azabicycloalkanes, which is now described.While other synthetic strategies will be apparent to those of skill inthe art, 2-(arylalkyl)-1-azabicycloalkanes can be made by reduction ofaldol condensation products formed from aldehydes and certainazabicyclic ketones. Thus, when 3-quinuclidinone hydrochloride isreacted with pyridine-3-carboxaldehyde (available from Aldrich ChemicalCompany), in the presence of methanolic potassium hydroxide,2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one results.Stepwise reduction of the conjugated enone functionality can beaccomplished through several different sequences, to provide2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane. For instance,catalytic hydrogenation (palladium catalyst) of the enone produces thesaturated ketone,2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one, an intermediatein the synthesis of compounds of the present invention (see sectionentitled “Substituted-2-(Arylalkyl)-1-azabicycloalkanes”). Reduction ofthe ketone to the alcohol can be accomplished, for example, using sodiumborohydride, aluminum isopropoxide, or other reagents known in the artof chemical synthesis for carrying out similar reductions. The alcohol,2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol, is a mixture ofcis and trans diastereomers (with the former predominating) and is alsoan intermediate in the synthesis of compounds of the present invention(see section entitled “Substituted-2-(Arylalkyl)-1-azabicycloalkanes”).The choice of reducing agent affects the cis/trans ratio. The alcoholcan then be converted to the corresponding chloride,3-chloro-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane, usingthionyl chloride or similar reagents. The chloride can then be reducedto 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane, for example, usingRaney nickel. The chloro intermediate can also be converted into thealkene, 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-2-ene, which canthen be reduced to the alkane by catalytic hydrogenation.1,8-Diazabicyclo[5.4.0]undec-7-ene can be used for thedehydrohalogenation reaction, according to the method of Wolkoff, J.Org. Chem. 47: 1944 (1982). Alternatively, the2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one can then beconverted into 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane byfirst reducing the ketone functionality using sodium borohydride. Theresulting unsaturated alcohol,2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-ol, is treatedwith thionyl chloride (to make the chloro compound), followed by Raneynickel (to reductively remove the chloro moiety), and then hydrogenated,for example, over a palladium catalyst (to reduce the double bond) togive the alkane. It is noteworthy that, when this latter route isemployed, allylic rearrangements are observed. For instance, thematerial resulting from Raney nickel reduction of the chloro compound isa mixture of exocyclic and endocyclic alkenes, with the latterpredominating. This route provides access to both2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octane and2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-2-ene.

In an alternative approach, 2-(arylalkyl)-1-azabicycloalkanes can bemade by reacting aryl-containing organometallic compounds withazabicyclic carbonyl compounds and subsequently reducing the resultingalcohol, using the methods described above, to the alkane. For example,2-((3-pyridinyl)hydroxymethyl)-1-azabicyclo[2.2.2]octane can be producedby reacting 3-pyridinyllithium with quinuclidine-2-carboxaldehyde.Reaction of the alcohol with thionyl chloride to produce thecorresponding chloride, and subsequent reduction with Raney nickel, willgive 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane. Synthesis of therequisite quinuclidine-2-carboxaldehyde is described by Ricciardi andDoukas, Heterocycles 24: 971 (1986), and the 3-pyridinyllithium can begenerated from 3-bromopyridine by treatment with n-butyllithium in etheror toluene at low temperature (Cai et al., Tetrahedron Lett. 43: 4285(2002)).

The manner in which 2-((4-, 5-, and6-substituted-3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanes can besynthesized can vary. For example, 5-bromopyridine-3-carboxaldehyde and3-quinuclidinone hydrochloride (commercially available from Aldrich) canbe reacted together in the presence of methanolic potassium hydroxide asdescribed in Neilsen and Houlihan, Org. React. 16: 1 (1968). The aldolcondensation product,2-((5-bromo-3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one, canthen be treated with sodium borohydride to yield the alcohol,2-((5-bromo-3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-ol, as acrystalline solid. This intermediate is reacted with neat thionylchloride at room temperature to give3-chloro-2-((5-bromo-3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octanedihydrochloride as a pure crystalline solid. Reductive removal of thechlorine can be accomplished using lithium trimethoxyaluminum hydrideand copper iodide as described by Masamune et al., J. Am. Chem. Soc. 95:6452 (1973) to give the desired product,2-((5-bromo-3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octane, as acrystalline solid. This methylene intermediate can then be converted tothe desired product,2-((5-bromo-3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane, byhydrogenation in the presence of palladium catalyst. The isomericcompounds, 2-((4-bromo-3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane and2-((6-bromo-3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane can beprepared in a similar manner by replacing5-bromopyridine-3-carboxaldehyde with 4-bromopyridine-3-carboxaldehydeor 6-bromopyridine-3-carboxaldehyde, respectively, in the syntheticapproach given above.

The required aldehyde, 5-bromopyridine-3-carboxaldehyde, can be preparedfrom 5-bromonicotinic acid (commercially available from Aldrich ChemicalCompany and Lancaster Synthesis, Inc.). The 5-bromonicotinic acid can betreated with ethyl chloroformate to form a mixed anhydride, which canthen be reduced, for example, with lithium aluminum hydride intetrahydrofuran (THF) at −78° C., to afford5-bromo-3-(hydroxymethyl)pyridine, as reported by Ashimori et al., Chem.Pharm. Bull. 38(9): 2446 (1990). Alternatively, the 5-bromonicotinicacid can be esterified, for example, in the presence of sulfuric acidand ethanol and the intermediate ethyl ester reduced with an excess ofsodium borohydride to yield 5-bromo-3-(hydroxymethyl)pyridine, accordingto the techniques reported in Nutaitis et al., Org. Prep. and Proc. Int.24: 143 (1992). The resulting 5-bromo-3-(hydroxymethyl)pyridine can thenbe converted to 5-bromo-3-pyridinecarboxaldehyde by Swern oxidationusing oxalyl chloride and dimethylsulfoxide, according to the methods ofStocks et al., Tetrahedron Lett. 36(36): 6555 (1995) and Mancuso et al.,J. Org. Chem. 44(23): 4148 (1979). The aldehyde,4-bromopyridine-3-carboxaldehyde can be synthesized according tomethodology described in PCT WO 94/29893 by Chin et al. or bymethodology described by Ojea et al., Synlett. 6: 622 (1995).6-Bromopyridine-3-carboxaldehyde can be prepared according to proceduresdescribed in Windschief and Voegtle, Synthesis 1: 87 (1994) or GermanPatent No. 93/4320432 to Fey et al.

The methods described above are applicable to the preparation of avariety of 2-(arylmethyl)-1-azabicyclo[2.2.2]octanes,2-(arylmethylene)-1-azabicyclo[2.2.2]octanes and2-(arylmethyl)-1-azabicyclo[2.2.2]oct-2-enes by variation of thealdehyde component of the aldol condensation using no more than routineexperimentation. Both substituted and unsubstituted, carbocyclic andheterocyclic aromatic aldehydes can be used.

Those skilled in the art of organic synthesis will appreciate that thereactivity of substituents borne by the aldehyde must be evaluatedcarefully, as some substituents may be transformed by the reactionconditions employed. Examples of groups that are potentially reactiveunder the reaction conditions are —OH, —SH, —NH₂ and —CO₂H. Suitableprotecting groups or synthons for such substituents can be used, as arewell known to those of skill in the art, for substituents that mightotherwise be transformed during the aldol condensation or subsequentreaction steps. These “protecting” groups can be chosen, introduced andcleaved in accordance to methods described by Greene and Wuts,Protective Groups in Organic Synthesis 2^(nd) ed., Wiley—IntersciencePub. (1991). Examples of suitable synthons are described, for example,in Hase, Umpoled Synthons: A Survey of Sources and Uses in Synthesis,Wiley, Europe (1987). The contents of these publications are herebyincorporated by reference in their entirety.

Variation in the Length of the Linker

The compounds of the present invention can contain more than one carbonin the linker between the heteroaromatic ring and azabicyclic ringfunctionalities. The manner in which such compounds as2-(2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octane,2-(3-(3-pyridinyl)propyl)-1-azabicyclo[2.2.2]octane, and2-(4-(3-pyridinyl)butyl)-1-azabicyclo[2.2.2]octane can be prepared canvary. For example, 2-(2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octanecan be prepared by different methods. In one approach,3-pyridineacetaldehyde (also known as 2-(3-pyridinyl)ethanal) can becondensed with 3-quinuclidinone hydrochloride (commercially availablefrom Aldrich Chemical Company) in a directed aldol reaction using a basesuch as potassium hydroxide or sodium hydroxide in methanol or sodiumethoxide in ethanol. Directed aldol condensations between an aldehydeand a ketone with accompanying reaction modifications, includingprocedures utilizing various enol ethers, are described in Smith andMarch, Advanced Organic Chemistry, Reactions, Mechanisms, and Structure,5^(th) ed., Wiley-Interscience Pubs., pp. 1220-1221 (2001). Depending onreaction conditions, condensation products may or may not spontaneouslydehydrate to give enones. Thus, it may be necessary to treat theintermediate condensation products, such as2-(1-hydroxy-2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octan-3-one, underany of various dehydration protocols, known to those skilled in the art,to generate, in this case,2-(2-(3-pyridinyl)ethylidene)-1-azabicyclo[2.2.2]octan-3-one. Thecarbon-carbon double bond of this unsaturated ketone can be reduced byhydrogenation to give the ketone,2-(2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octan-3-one, which can befurther reduced under Wolff-Kishner conditions to yield2-(2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octane. Methods similar tothose described by Yanina et al., Khim.-Farm. Zh. 21(7): 808 (1987) canbe used for the latter reductions. Alternatively, the ketone can bereduced to the alcohol using sodium borohydride and the alcoholsubsequently reduced to the alkane by conversion to the chlorointermediate (using thionyl chloride), followed by Raney nickelreduction. Replacement of 2-(3-pyridinyl)ethanal in the above syntheticapproach with 3-(3-pyridinyl)propanal leads to2-(3-(3-pyridinyl)propyl)-1-azabicyclo[2.2.2]octane and thecorresponding synthetic intermediates. Replacement of2-(3-pyridinyl)ethanal in the above synthetic approach with4-(3-pyridinyl)butanal leads to2-(4-(3-pyridinyl)butyl)-1-azabicyclo[2.2.2]octane and the correspondingsynthetic intermediates. In all cases, the saturated ketone and alcoholintermediates provide a synthetic approach to compounds of the presentinvention (see section entitled “Substituted2-(Arylalkyl)-1-azabicycloalkanes”).

The requisite aldehydes for the above aldol condensations can beprepared by various methods. In one approach, 3-pyridineacetaldehyde(also known as 2-(3-pyridinyl)ethanal) can be prepared from3-pyridinylacetic acid hydrochloride (commercially available fromAldrich Chemical Company and Lancaster Synthesis, Inc.) through theintermediacy of the ester. Thus, treatment with trimethylsilyl chlorideand triethylamine generates the trimethylsilyl ester, which can then bereduced with diisobutylaluminum hydride according to the method ofChandrasekhar et al., Tet. Lett. 39: 909 (1998). Alternatively,3-pyridineacetaldehyde can be prepared from 3-(3-pyridinyl)acrylic acid(commercially available from Aldrich Chemical Company and LancasterSynthesis, Inc.) using the method of Hey et al., J. Chem. Soc. Part II:1678 (1950). In this method, 3-(3-pyridinyl)acrylic acid can beconverted to its acid chloride by treatment with thionyl chloride.Subsequent treatment of the acid chloride with ammonia, according to themethod of Panizza, Helv. Chim. Acta 24: 24E (1941), yieldsβ-(3-pyridinyl)acrylamide. Hofmann rearrangement of the latter amide bytreatment with sodium hypochlorite affords methyl2-(3-pyridinyl)vinylcarbamate, which can be hydrolyzed with refluxing 3M sulfuric acid in ethanol to give 3-pyridineacetaldehyde, which can beisolated as its 2,4-dinitrophenylhydrazone sulfate.

The aldehyde, 3-(3-pyridinyl)propanal, which can be used to prepare2-(3-(3-pyridinyl)propyl)-1-azabicyclo[2.2.2]octane and relatedcompounds, can be prepared from 3-(3-pyridinyl)propanol (commerciallyavailable from Aldrich Chemical Company and Lancaster Synthesis, Inc.).Oxidation of the latter alcohol, for example, with lead acetate inpyridine, according to the method of Ratcliffe et al., J. Chem. Soc.,Perkin Trans. 1 8: 1767 (1985), affords 3-(3-pyridinyl)propanal.Alternatively, 3-(3-pyridinyl)propanal can be prepared by Swernoxidization of 3-(3-pyridinyl)propanol using oxalyl chloride in dimethylsulfoxide and dichloromethane according to the methods of Stocks et al.,Tet. Lett. 36(36): 6555 (1995) and Mancuso et al., J. Org. Chem. 44(23):4148 (1979).

The aldehyde, 4-(3-pyridinyl)butanal, required for the preparation of2-(4-(3-pyridinyl)butyl)-1-azabicyclo[2.2.2]octane and related compoundscan be prepared from 3-(3-pyridinyl)propanol (commercially availablefrom Aldrich Chemical Company and Lancaster Synthesis, Inc.) by ahomologative process according to the method of Solladié et al.,Tetrahedron:Asymmetry 8(5): 801 (1997). Treatment of3-(3-pyridinyl)propanol with tribromoimidazole and triphenylphosphineyields 1-bromo-3-(3-pyridinyl)propane, which can be condensed with thelithium salt of 1,3-dithiane. Hydrolysis of the dithianyl group of theresulting compound with aqueous mercuric chloride and mercuric oxideaffords 4-(3-pyridinyl)butanal.

In yet another approach to the synthesis of2-(2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octane, 3-picoline can beconverted into its lithio derivative, 3-(lithiomethyl)pyridine, asdescribed by Fraser et al., J. Org. Chem. 50: 3232 (1985), and reactedwith quinuclidine-2-carboxaldehyde. The resulting alcohol,2-(1-hydroxy-2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octane, can thenbe converted to 2-(2-(3-pyridinyl)ethyl)-1-azabicyclo[2.2.2]octane byone of the sequences previously described (i.e., dehydration, catalytichydrogenation; conversion to the chloride, dehydrohalogenation,catalytic hydrogenation; conversion to the chloride, Raney nickelreduction). The synthesis of quinuclidine-2-carboxaldehyde is describedby Ricciardi and Doukas, Heterocycles 24: 971 (1986).

Variation in the Azabicycle

Compounds of the present invention include those in which the azabicycleis 1-azabicyclo[2.2.1]heptane. The manner in which2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.1]heptanes can be synthesizedcan vary. In one approach, pyridine-3-carboxaldehyde can be reacted with1-azabicyclo[2.2.1]heptan-3-one in an aldol condensation. The aldolcondensation product,2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.1]heptan-3-one, can then beconverted, using reaction sequences described previously for the1-azabicyclo[2.2.2]octane case, into2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.1]heptane. A variety ofunsubstituted or substituted, carbocyclic or heterocyclic aromaticaldehydes can be employed in this sequence. The requisite1-azabicyclo[2.2.1]heptan-3-one can be synthesized, for example,according to the methods of Wadsworth et al., U.S. Pat. No. 5,217,975and Street et al., J. Med. Chem. 33: 2690 (1990).

The present invention includes compounds in which the azabicycle is1-azabicyclo[3.2.1]octane, such as2-((3-pyridinyl)methyl)-1-azabicyclo[3.2.1]octane. An approach similarto that described for the2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.1]heptane case can be used tosynthesize 2-((3-pyridinyl)methyl)-1-azabicyclo[3.2.1]octane. Thus, thealdol condensation of pyridine-3-carboxaldehyde and1-azabicyclo[3.2.1]octan-3-one (see Sternbach et al. J. Am. Chem. Soc.74: 2215 (1952)) will generate isomeric products,2-((3-pyridinyl)methylene)-1-azabicyclo[3.2.1]octan-3-one and4-((3-pyridinyl)methylene)-1-azabicyclo[3.2.1]octan-3-one. These canthen be chromatographically separated and the2-((3-pyridinyl)methylene)-1-azabicyclo[3.2.1]octan-3-one treated asdescribed before to produce2-((3-pyridinyl)methyl)-1-azabicyclo[3.2.1]octane. A variety ofunsubstituted or substituted, carbocyclic or heterocyclic aromaticaldehydes can be employed in this sequence. The requisite1-azabicyclo[3.2.1]octan-3-one can be synthesized, for example,according to the method of Thill and Aaron, J. Org. Chem. 33: 4376(1969). In all cases, the saturated ketone and alcohol intermediatesprovide a synthetic approach to compounds of the present invention.

Substituted 2-(Arylalkyl)-1-azabicycloalkanes

It will be immediately recognized, by those skilled in the art, that theintermediates generated during the described syntheses of2-(arylalkyl)-1-azabicycles present many opportunities for synthesizingsubstituted derivatives. For instance, conjugated enones, such as2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one, are known toundergo 1,4-addition reactions when exposed to organolithium andorganomagnesium reagents in the presence of cuprous salts. Suchchemistry is reviewed by Posner, Org. React. 19: 1 (1972) and House,Acc. Chem. Res. 9: 59 (1976). In some cases conjugate 1,4-addition isobserved even in the absence of cuprous salts. Thus, treatment of2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one withphenylmagnesium bromide in ether at −10° C. gives2-(1-phenyl-1-(3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane-3-one asthe predominant product. This ketone can then be treated with sodiumborohydride to yield the alcohol,2-(1-phenyl-1-(3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol. Thisalcohol can then be reacted with neat thionyl chloride at roomtemperature to give3-chloro-2-(1-phenyl-1-(3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane asa crystalline solid. The chlorine can be removed by hydrogenation in thepresence of Raney nickel, as described by de Koning, Org. Prep. Proced.Int. 7: 31 (1975), to give2-(1-phenyl-1-(3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane. Usingvariations on this approach, a number of alkyl and aryl substituents canbe installed on the linker moiety between the heteroaromatic (e.g.,pyridine) and azabicyclic (e.g., quinuclidine) rings.

The saturated ketone intermediates, such as2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one, also presentopportunities for derivatization. One example is the reaction withphosphorus ylids (Wittig and Horner-Emmons reagents) to give alkenes.These alkenes can subsequently be reduced to alkanes by catalytichydrogenation, providing a means of producing2-((heteroaryl)alkyl)-1-azabicycles with alkyl and substituted alkylsubstituents at the 3-position of the azabicycle. Thus, by way ofexample, 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one reactswith methylenetriphenylphosphorane to give3-methylene-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane.Hydrogenation of this alkene, for example, over palladium on carboncatalyst, yields3-methyl-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane aspredominantly the cis diastereomer.

Another illustration of derivatization of saturated ketone intermediatesis the reductive amination to give amines. Thus,2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one reacts withammonium formate, zinc chloride and sodium cyanoborohydride to give3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane aspredominantly the cis diastereomer. Likewise, reaction of2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one with methylamineand sodium cyanoborohydride provides3-(methylamino)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane. Theseamine derivatives can be used as a template for library formation byreacting them with a variety of acylating agents (e.g., acid chlorides,acid anhydrides, active esters, and carboxylic acids in the presence ofcoupling reagents) and isocyanates to produce2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanes with amide and ureasubstituents in the 3-position of the 1-azabicyclo[2.2.2]octane, both ofwhich classes are compounds of the present invention. Commerciallyunavailable isocyanates can be prepared in situ from correspondingamines and triphosgene in the presence of triethylamine. Suchderivatives can be produced as single enantiomers, using the singleenantiomers of 3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octaneand 3-(methylamino)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane asstarting materials. For instance, the (2R,3R)- and(2S,3S)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanes canbe produced by resolution of the cis3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane, for example,using diastereomeric amides. Thus, when the cis amine is reacted with achiral acid such as (S)—N-(tert-butoxycarbonyl)proline using a suitablecoupling agent such as diphenylchlorophosphate, a pair of diastereomericamides, separable by reverse phase chromatography, is produced. Theseparated proline amides can then be deprotected, for example, bytreatment with trifluoroacetic acid (to remove the tert-butoxycarbonylprotecting group) and then the proline can be cleaved from the desiredamine, for example, using Edman degradation conditions (i.e.,phenylisothiocyanate, followed by trifluoroacetic acid).

Alternatively, racemic reductive amination products such as3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane can beseparated into their enantiomers by fractional crystallization of thedi-O-p-toluoyltartaric acid salts. Both the D (S,S) and L (R,R) isomersof this acid are commercially available (Aldrich Chemical Company).Thus, combination of the racemic cis3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane with 0.5 molarequivalents of either enantiomer of di-O-p-toluoyltartaric acid yields adiastereomeric salt mixture, from which a single diastereomerprecipitates from methanol solution.

The saturated alcohol intermediates, such as2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol, can also serve astemplates for compound libraries. For instance, ethers can be generatedfrom these alcohols, for example, using either Mitsunobu or Williamsonconditions. Thus, by way of example, when2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol is reacted withphenol via Mitsunobu coupling with diethylazidocarboxylate andtriphenylphosphine (Guthrie et al., J. Chem. Soc., Perkin Trans I 45:2328 (1981)),3-phenoxy-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane results.Similarly, when 2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-olis treated with sodium hydride and methyl iodide, the unsaturated ether,3-methoxy-2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octane, isformed. This gives the saturated ether,3-methoxy-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane(predominantly cis), upon catalytic hydrogenation.

The saturated alcohol intermediates can also be reacted with acylatingagents (e.g., acid chlorides and anhydrides) and isocyanates to produceesters and carbamates, respectively. Thus, by way of example,2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol reacts withphenylisocyanate to yield3-(N-phenylcarbamoyloxy)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane.Such carbamate compounds are compounds of the present invention.

Such derivatives can be produced as single enantiomers, using the singleenantiomers of 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol asstarting materials. For instance, the (2R,3R)- and(2S,3S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ols can beproduced by resolution of the cis2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol, usingdiastereomeric esters. Thus, when the cis alcohol is reacted with(S)-2-methoxy-2-phenylacetic acid and N,N-dicyclohexylcarbodiimide, apair of diastereomeric esters, separable by reverse phasechromatography, is produced. The separated esters can then be hydrolyzedto the enantiomerically pure alcohols, for example, using potassiumhydroxide in methanol. Alternatively (1S)-(−)-camphanic acid chloridecan be used to produce diastereomeric camphanate esters of cis2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol. The esters arethen fractionally crystallized, using the procedure described by Swaim,et al., J. Med. Chem. 38: 4793 (1995).

A number of compounds possessing substituents at the 5-position of thepyridine ring can be prepared from2-((5-bromo-3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane, the synthesisof which has already been described. For example, the5-amino-substituted compound can be prepared from the corresponding5-bromo compound, using ammonia in the presence of a copper catalystaccording to the general method of Zwart et al., Recueil Tray. Chim.Pays-Bas 74: 1062 (1955). 5-Alkylamino-substituted compounds can beprepared in a similar manner. 5-Alkoxy-substituted analogs can beprepared from the corresponding 5-bromo compounds by heating with asodium alkoxide in N,N-dimethylformamide or by use of a copper catalystaccording to the general techniques described by Comins et al., J. Org.Chem. 55: 69 (1990) and den Hertog et al., Recueil Tray. Chim. Pays-Bas74: 1171 (1955). 5-Ethynyl-substituted compounds can be prepared fromthe appropriate 5-bromo compounds by palladium-catalyzed coupling using2-methyl-3-butyn-2-ol, followed by base (sodium hydride) catalyzeddeprotection, according to the general techniques described by Cosfordet al., J. Med. Chem. 39: 3235 (1996). The 5-ethynyl analogs can beconverted into the corresponding 5-ethenyl, and subsequently to thecorresponding 5-ethyl analogs by successive catalytic hydrogenationreactions. The 5-phenyl analogs can be prepared from the 5-bromocompounds by Suzuki coupling with phenylboronic acid. Substitutedphenylboronic acids can also be used. The 5-azido-substituted analogscan be prepared from the corresponding 5-bromo compounds by reactionwith sodium azide in N,N-dimethylformamide. 5-Alkylthio-substitutedanalogs can be prepared from the corresponding 5-bromo compound byreaction with an appropriate alkylmercaptan in the presence of sodium,using techniques known to those skilled in the art of organic synthesis.

A number of 5-substituted analogs of the aforementioned compounds can besynthesized from the corresponding 5-amino compounds via the 5-diazoniumsalt intermediates. Among the other 5-substituted analogs that can beproduced from 5-diazonium salt intermediates are: 5-hydroxy analogs,5-fluoro analogs, 5-chloro analogs, 5-bromo analogs, 5-iodo analogs,5-cyano analogs, and 5-mercapto analogs. These compounds can besynthesized using the general techniques set forth in Zwart et al.,Recueil Tray. Chim. Pays-Bas 74: 1062 (1955). For example,5-hydroxy-substituted analogs can be prepared from the reaction of thecorresponding 5-diazonium salt intermediates with water.5-Fluoro-substituted analogs can be prepared from the reaction of the5-diazonium salt intermediates with fluoroboric acid.5-Chloro-substituted analogs can be prepared from the reaction of the5-amino compounds with sodium nitrite and hydrochloric acid in thepresence of copper chloride. 5-Cyano-substituted analogs can be preparedfrom the reaction of the corresponding 5-diazonium salt intermediateswith potassium copper cyanide. 5-Amino-substituted analogs can also beconverted to the corresponding 5-nitro analogs by reaction with fumingsulfuric acid and peroxide, according to the general techniquesdescribed in Morisawa, J. Med. Chem. 20: 129 (1977) for converting anaminopyridine to a nitropyridine. Appropriate 5-diazonium saltintermediates can also be used for the synthesis of mercapto-substitutedanalogs using the general techniques described in Hoffman et al., J.Med. Chem. 36: 953 (1993). The 5-mercapto-substituted analogs can inturn be converted to the 5-alkylthio-substituted analogs by reactionwith sodium hydride and an appropriate alkyl bromide. 5-Acylamidoanalogs of the aforementioned compounds can be prepared by reaction ofthe corresponding 5-amino compounds with an appropriate acid anhydrideor acid chloride, using techniques known to those skilled in the art oforganic synthesis.

5-Hydroxy-substituted analogs of the aforementioned compounds can beused to prepare corresponding 5-alkanoyloxy-substituted compounds byreaction with the appropriate acid, acid chloride, or acid anhydride.Likewise, the 5-hydroxy compounds are precursors of both the 5-aryloxyand 5-heteroaryloxy analogs via nucleophilic aromatic substitution atelectron deficient aromatic rings (e.g., 4-fluorobenzonitrile and2,4-dichloropyrimidine). Such chemistry is well known to those skilledin the art of organic synthesis. Ether derivatives can also be preparedfrom the 5-hydroxy compounds by alkylation with alkyl halides and asuitable base or via Mitsunobu chemistry, in which a trialkyl- ortriarylphosphine and diethyl azodicarboxylate are typically used. SeeHughes, Org. React. (N.Y.) 42: 335 (1992) and Hughes, Org. Prep. Proced.Int. 28: 127 (1996) for typical Mitsunobu conditions.

5-Cyano-substituted analogs of the aforementioned compounds can behydrolyzed to afford the corresponding 5-carboxamido-substitutedcompounds. Further hydrolysis results in formation of the corresponding5-carboxylic acid-substituted analogs. Reduction of the5-cyano-substituted analogs with lithium aluminum hydride yields thecorresponding 5-aminomethyl analogs. 5-Acyl-substituted analogs can beprepared from corresponding 5-carboxylic acid-substituted analogs byreaction with an appropriate alkyllithium reagent using techniques knownto those skilled in the art of organic synthesis.

5-Carboxylic acid-substituted analogs of the aforementioned compoundscan be converted to the corresponding esters by reaction with anappropriate alcohol and acid catalyst. Compounds with an ester group atthe 5-pyridinyl position can be reduced, for example, with sodiumborohydride or lithium aluminum hydride to produce the corresponding5-hydroxymethyl-substituted analogs. These analogs in turn can beconverted to compounds bearing an alkoxymethyl moiety at the 5-pyridinylposition by reaction, for example, with sodium hydride and anappropriate alkyl halide, using conventional techniques. Alternatively,the 5-hydroxymethyl-substituted analogs can be reacted with tosylchloride to provide the corresponding 5-tosyloxymethyl analogs. The5-carboxylic acid-substituted analogs can also be converted to thecorresponding 5-alkylaminoacyl analogs by sequential treatment withthionyl chloride and an appropriate alkylamine. Certain of these amidesare known to readily undergo nucleophilic acyl substitution to produceketones. Thus, the so-called Weinreb amides (N-methoxy-N-methylamides)react with aryllithium reagents to produce the corresponding diarylketones. For example, see Selnick et al., Tet. Lett. 34: 2043 (1993).

5-Tosyloxymethyl-substituted analogs of the aforementioned compounds canbe converted to the corresponding 5-methyl-substituted compounds byreduction with lithium aluminum hydride. 5-Tosyloxymethyl-substitutedanalogs of the aforementioned compounds can also be used to produce5-alkyl-substituted compounds via reaction with an alkyl lithium salt.5-Hydroxy-substituted analogs of the aforementioned compounds can beused to prepare 5-N-alkylcarbamoyloxy-substituted compounds by reactionwith N-alkylisocyanates. 5-Amino-substituted analogs of theaforementioned compounds can be used to prepare5-N-alkoxycarboxamido-substituted compounds by reaction with alkylchloroformate esters, using techniques known to those skilled in the artof organic synthesis.

Analogous chemistries to those described hereinbefore, for thepreparation of the 5-substituted analogs of compounds of the presentinvention, can be employed for the synthesis of 2-, 4-, and6-substituted analogs. Starting materials for these transformationsinclude the aforementioned 2-((4- and6-bromo-3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanes, as well as the2-((2-, 4-, and 6-amino-3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanes,which are accessible from2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane via the Chichibabinreaction (Lahti et al., J. Med. Chem. 42: 2227 (1999).

The compounds can be isolated and purified using methods well known tothose of skill in the art, including, for example, crystallization,chromatography and/or extraction.

The compounds of Formulas 1 and 2 can be obtained in optically pure formby separating their racemates in accordance with the customary methodsor by using optically pure starting materials.

The compounds of Formulas 1 and 2 can optionally be converted intoaddition salts with a mineral or organic acid by the action of such anacid in an appropriate solvent, for example, an organic solvent such asan alcohol, a ketone, an ether or a chlorinated solvent. These saltslikewise form part of the invention.

Representative pharmaceutically acceptable salts include, but are notlimited to, benzenesulphonate, bromide, chloride, citrate,ethanesulphonate, fumarate, gluconate, iodate, maleate, isethionate,methanesulphonate, methylenebis(β-oxynaphthoate), nitrate, oxalate,palmoate, phosphate, salicylate, succinate, sulphate, tartrate,theophyllinacetate, p-toluenesulphonate, hemigalactarate and galactaratesalts.

Imaging Agents

Certain compounds of the present invention (e.g., the amide derivativesof 3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane) can besynthesized in such a manner as to incorporate a radionuclide useful indiagnostic imaging. Of particular interest are those compounds thatinclude radioactive isotopic moieties such as ¹¹C, ¹⁸F, ⁷⁶Br, ¹²³I,¹²⁵I, and the like. The compounds can be radiolabeled at any of avariety of positions. For example, a radionuclide of the halogen seriesmay be used within an alkyl halide or aryl halide moiety orfunctionality; while a radionuclide such as ¹¹C may be used with analkyl (e.g., methyl) moiety or functionality.

For instance, commercially available p-(dimethylamino)benzoic acid(Aldrich) is converted, by treatment with iodomethane in methanol, intop-(trimethylammonium)benzoate, as described by Willstaetter and Kahn,Chem. Ber. 37: 406 (1904). The displacement of the trimethylammoniumgroup by fluoride has been reported, in similar compounds, by severalresearchers (see, for instance, Mach et al., J. Med. Chem. 36: 3707(1993) and Jalalian et al., J. Labelled Compd. Radiopharm. 43: 545(2000)). These nucleophilic aromatic substitution reactions aretypically carried out in dimethylsulfoxide (with or without watercosolvent), using KF or CsF as the source of fluoride ion (when KF isused, often Kryptofix® 222 is added). When ¹⁸F⁻ is used in such adisplacement, p-¹⁸fluorobenzoic acid results. This carboxylic acid canbe rapidly coupled to3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane), using any ofa variety of techniques known to those skilled in the art (some of whichare described previously), to generateN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-4-¹⁸fluorobenzamide,which can be used to specifically image α7 nAChRs.

Those compounds that include an amide or urea functionality (i.e., Xand/or Z ═NR′, R′═H) can be readily radiolabeled by alkylating the amideor urea group with a radiolabeled haloalkane in the presence of a base(i.e., to form substituted compounds where R′ is a radiolabeled loweralkyl, cycloalkyl or arylalkyl moiety). One example of such aradiolabeled haloalkane is ¹¹C-labeled methyl iodide. Methods similar tothose described by A. G. Horti et al., J. Med. Chem. 41: 4199-4206(1998) can be used. The resulting N—[¹¹C]methyl-containing compounds canbe purified by semi-preparative or preparative HPLC and briefly isolatedfor reconstitution. The ¹¹C-labeled methyl iodide can be preparedaccording to the general method described by B. Långström et al. J.Nucl. Med. 28(6):1037-1040 (1987). Thus, nitrogen gas is irradiated with10 MeV protons producing ¹¹C-carbon dioxide. The ¹¹C-carbon dioxide istrapped using 4 Å molecular sieves, which are subsequently stored in alead shield. The ¹¹C-carbon dioxide is liberated from the 4 Å molecularsieves by heating to ˜250° C. The ¹¹C-carbon dioxide is then carried ina stream of nitrogen and trapped in a vessel containing lithium aluminumhydride in tetrahydrofuran. The tetrahydrofuran is removed by heatingand a nitrogen flow, and the lithium aluminum hydride complex is thenhydrolyzed by treatment with hydriodic acid, affording ¹¹C-labeledmethyl iodide. The ¹¹C-labeled methyl iodide can be transferred bycarrier gas to the reaction vessel containing the material to bemethylated. The required amide- and urea-containing precursor compoundsare described in detail above, and the resulting radiolabeled compoundscan also be used to specifically image α7 nAChRs.

II. Pharmaceutical Compositions

The compounds described herein can be incorporated into pharmaceuticalcompositions and used to prevent a condition or disorder in a subjectsusceptible to such a condition or disorder, and/or to treat a subjectsuffering from the condition or disorder. The pharmaceuticalcompositions described herein include one or more compounds of Formulas1 and 2 and/or pharmaceutically acceptable salts thereof. Chiralcompounds can be employed as racemic mixtures or as pure enantiomers.

The manner in which the compounds are administered can vary. Thecompositions are preferably administered orally (e.g., in liquid formwithin a solvent such as an aqueous or non-aqueous liquid, or within asolid carrier). Preferred compositions for oral administration includepills, tablets, capsules, caplets, syrups, and solutions, including hardgelatin capsules and time-release capsules. Compositions can beformulated in unit dose form, or in multiple or subunit doses. Preferredcompositions are in liquid or semisolid form. Compositions including aliquid pharmaceutically inert carrier such as water or otherpharmaceutically compatible liquids or semisolids can be used. The useof such liquids and semisolids is well known to those of skill in theart.

The compositions can also be administered via injection, i.e.,intravenously, intramuscularly, subcutaneously, intraperitoneally,intraarterially, intrathecally; and intracerebroventricularly.Intravenous administration is the preferred method of injection.Suitable carriers for injection are well known to those of skill in theart and include 5% dextrose solutions, saline, and phosphate-bufferedsaline. The compounds can also be administered as an infusion orinjection (e.g., as a suspension or as an emulsion in a pharmaceuticallyacceptable liquid or mixture of liquids).

The formulations can also be administered using other means, forexample, rectal administration. Formulations useful for rectaladministration, such as suppositories, are well known to those of skillin the art. The compounds can also be administered by inhalation (e.g.,in the form of an aerosol either nasally or using delivery articles ofthe type set forth in U.S. Pat. No. 4,922,901 to Brooks et al., thedisclosure of which is incorporated herein in its entirety); topically(e.g., in lotion form); or transdermally (e.g., using a transdermalpatch, using technology that is commercially available from Novartis andAlza Corporation). Although it is possible to administer the compoundsin the form of a bulk active chemical, it is preferred to present eachcompound in the form of a pharmaceutical composition or formulation forefficient and effective administration.

Exemplary methods for administering such compounds will be apparent tothe skilled artisan. The usefulness of these formulations can depend onthe particular composition used and the particular subject receiving thetreatment. These formulations can contain a liquid carrier that can beoily, aqueous, emulsified or contain certain solvents suitable to themode of administration.

The compositions can be administered intermittently or at a gradual,continuous, constant or controlled rate to a warm-blooded animal (e.g.,a mammal such as a mouse, rat, cat, rabbit, dog, pig, cow, or monkey),but advantageously are administered to a human being. In addition, thetime of day and the number of times per day that the pharmaceuticalformulation is administered can vary.

Preferably, upon administration, the active ingredients interact withreceptor sites within the body of the subject that affect thefunctioning of the CNS. More specifically, in treating a CNS disorder,preferable administration is designed to optimize the effect upon thoserelevant nicotinic acethylcholine receptor (nAChR) subtypes that have aneffect upon the functioning of the CNS, while minimizing the effectsupon muscle-type receptor subtypes. Other suitable methods foradministering the compounds of the present invention are described inU.S. Pat. No. 5,604,231 to Smith et al., the contents of which arehereby incorporated by reference.

In certain circumstances, the compounds described herein can be employedas part of a pharmaceutical composition with other compounds intended toprevent or treat a particular disorder. In addition to effective amountsof the compounds described herein, the pharmaceutical compositions canalso include various other components as additives or adjuncts.Exemplary pharmaceutically acceptable components or adjuncts which areemployed in relevant circumstances include antioxidants, free-radicalscavenging agents, peptides, growth factors, antibiotics, bacteriostaticagents, immunosuppressives, anticoagulants, buffering agents,anti-inflammatory agents, anti-pyretics, time-release binders,anesthetics, steroids, vitamins, minerals and corticosteroids. Suchcomponents can provide additional therapeutic benefit, act to affect thetherapeutic action of the pharmaceutical composition, or act towardspreventing any potential side effects that can be imposed as a result ofadministration of the pharmaceutical composition.

The appropriate dose of the compound is that amount effective to preventoccurrence of the symptoms of the disorder or to treat some symptoms ofthe disorder from which the patient suffers. By “effective amount”,“therapeutic amount” or “effective dose” is meant that amount sufficientto elicit the desired pharmacological or therapeutic effects, thusresulting in effective prevention or treatment of the disorder.

When treating a CNS disorder, an effective amount of compound is anamount sufficient to pass across the blood-brain barrier of the subject,to bind to relevant receptor sites in the brain of the subject and tomodulate the activity of relevant nAChR subtypes (e.g., provideneurotransmitter secretion, thus resulting in effective prevention ortreatment of the disorder). Prevention of the disorder is manifested bydelaying the onset of the symptoms of the disorder. Treatment of thedisorder is manifested by a decrease in the symptoms associated with thedisorder or an amelioration of the recurrence of the symptoms of thedisorder. Preferably, the effective amount is sufficient to obtain thedesired result, but insufficient to cause appreciable side effects.

The effective dose can vary, depending upon factors such as thecondition of the patient, the severity of the symptoms of the disorder,and the manner in which the pharmaceutical composition is administered.For human patients, the effective dose of typical compounds generallyrequires administering the compound in an amount sufficient to modulatethe activity of relevant nAChRs to effect neurotransmitter (e.g.,dopamine) release, but the amount should be insufficient to induceeffects on skeletal muscles and ganglia to any significant degree. Theeffective dose of compounds will of course differ from patient topatient, but in general includes amounts starting where CNS effects orother desired therapeutic effects occur but below the amount wheremuscular effects are observed.

The compounds, when employed in effective amounts in accordance with themethod described herein, are selective to certain relevant nAChRs, butdo not significantly activate receptors associated with undesirable sideeffects at concentrations at least greater than those required foreliciting the release of dopamine or other neurotransmitters. By this ismeant that a particular dose of compound effective in preventing and/ortreating a CNS disorder is essentially ineffective in elicitingactivation of certain ganglionic-type nAChRs at concentration higherthan 5 times, preferably higher than 100 times, and more preferablyhigher than 1,000 times than those required for modulation ofneurotransmitter release. This selectivity of certain compoundsdescribed herein against those ganglionic-type receptors responsible forcardiovascular side effects is demonstrated by a lack of the ability ofthose compounds to activate nicotinic function of adrenal chromaffintissue at concentrations greater than those required for activation ofdopamine release.

The compounds described herein, when employed in effective amounts inaccordance with the methods described herein, can provide some degree ofprevention of the progression of CNS disorders, ameliorate symptoms ofCNS disorders, and ameliorate to some degree of the recurrence of CNSdisorders. The effective amounts of those compounds are typically belowthe threshold concentration required to elicit any appreciable sideeffects, for example those effects relating to skeletal muscle. Thecompounds can be administered in a therapeutic window in which certainCNS disorders are treated and certain side effects are avoided. Ideally,the effective dose of the compounds described herein is sufficient toprovide the desired effects upon the CNS but is insufficient (i.e., isnot at a high enough level) to provide undesirable side effects.Preferably, the compounds are administered at a dosage effective fortreating the CNS disorders but less than ⅕, and often less than 1/10,the amount required to elicit certain side effects to any significantdegree.

Most preferably, effective doses are at very low concentrations, wheremaximal effects are observed to occur, with a minimum of side effects.Typically, the effective dose of such compounds generally requiresadministering the compound in an amount of less than 5 mg/kg of patientweight. Often, the compounds of the present invention are administeredin an amount from less than about 1 mg/kg patent weight and usually lessthan about 100 μg/kg of patient weight, but frequently between about 10μg to less than 100 μg/kg of patient weight. For compounds that do notinduce effects on muscle-type nicotinic receptors at low concentrations,the effective dose is less than 5 mg/kg of patient weight; and oftensuch compounds are administered in an amount from 50 μg to less than 5mg/kg of patient weight. The foregoing effective doses typicallyrepresent that amount administered as a single dose, or as one or moredoses administered over a 24-hour period.

For human patients, the effective dose of typical compounds generallyrequires administering the compound in an amount of at least about 1,often at least about 10, and frequently at least about 100 mg/24hr/patient. For human patients, the effective dose of typical compoundsrequires administering the compound which generally does not exceedabout 500, often does not exceed about 400, and frequently does notexceed about 300 mg/24 hr/patient. In addition, the compositions areadvantageously administered at an effective dose such that theconcentration of the compound within the plasma of the patient normallydoes not exceed 50 ng/mL, often does not exceed 30 ng/mL, and frequentlydoes not exceed 10 ng/mL.

III. Methods of Using the Compounds and/or Pharmaceutical Compositions

The compounds can be used to treat those types of conditions anddisorders for which other types of nicotinic compounds have beenproposed as therapeutics. See, for example, Williams et al., Drug NewsPerspec. 7(4):205 (1994), Arneric et al., CNS Drug Rev. 1(1):1 (1995),Arneric et al., Exp. Opin. Invest. Drugs 5(1):79 (1996), Bencherif etal., J. Pharmacol. Exp. Ther. 279:1413 (1996), Lippiello et al., J.Pharmacol. Exp. Ther. 279:1422 (1996), Damaj et al., J. Pharmacol. Exp.Ther. 291:390 (1999); Chiari et al., Anesthesiology 91:1447 (1999);Lavand'homme and Eisenbach, Anesthesiology 91:1455 (1999); Neuroscience(1997), Holladay et al., J. Med. Chem. 40(28):4169 (1997), Bannon etal., Science 279:77 (1998), PCT WO 94/08992, PCT WO 96/31475, and U.S.Pat. No. 5,583,140 to Bencherif et al., U.S. Pat. No. 5,597,919 to Dullet al., and U.S. Pat. No. 5,604,231 to Smith et al., the disclosures ofeach of which are incorporated herein by reference in their entirety.

More particularly, the compounds can be used to treat those types ofconditions and disorders for which nicotinic compounds with selectivityfor the α7 nAChR subtype have been proposed as therapeutics. See, forexample, Leonard et al., Schizophrenia Bulletin 22(3): 431 (1996),Freedman et al., Biological Psychiatry 38(1):22 (1995), Heeschen et al.,J. Clin. Invest. 100: 527 (2002), Utsugisawa et al., Molecular BrainResearch 106(1-2): 88 (2002), U.S. Patent Application 2002/0016371,Levin and Rezvani, Current Drug Targets: CNS and Neurological Disorders1(4): 423 (2002)), O'Neill et al., Current Drug Targets: CNS andNeurological Disorders 1(4): 399 (2002, Jeyarasasingam et al.,Neuroscience 109(2): 275 (2002)), Xiao et al., Proc. Nat. Acad. Sci.(US) 99(12): 8360 (2002)), PCT WO 99/62505, PCT WO 99/03859, PCT WO97/30998, PCT WO 01/36417, PCT WO 02/15662, PCT WO 02/16355, PCT WO02/16356, PCT WO 02/16357, PCT WO 02/16358, PCT WO 02/17358, Stevens etal., Psychopharm. 136: 320 (1998), Dolle et al., J. Labelled Comp.Radiopharm. 44: 785 (2001) and Macor et al., Bioorg. Med. Chem. Lett.11: 319 (2001) and references therein, the contents of each of which arehereby incorporated by reference in their entirety.

The compounds can also be used as adjunct therapy in combination withexisting therapies in the management of the aforementioned types ofdiseases and disorders. In such situations, it is preferably toadminister the active ingredients in a manner that minimizes effectsupon nAChR subtypes such as those that are associated with muscle andganglia. This can be accomplished by targeted drug delivery and/or byadjusting the dosage such that a desired effect is obtained withoutmeeting the threshold dosage required to achieve significant sideeffects. The pharmaceutical compositions can be used to ameliorate anyof the symptoms associated with those conditions, diseases anddisorders. Representative classes of disorders that can be treated arediscussed in detail below.

Treatment of CNS Disorders

Examples of conditions and disorders that can be treated includeneurological disorders and neurodegenerative disorders, and, inparticular, CNS disorders. CNS disorders can be drug induced; can beattributed to genetic predisposition, infection or trauma; or can be ofunknown etiology. CNS disorders comprise neuropsychiatric disorders,neurological diseases and mental illnesses, and includeneurodegenerative diseases, behavioral disorders, cognitive disordersand cognitive affective disorders. There are several CNS disorders whoseclinical manifestations have been attributed to CNS dysfunction (i.e.,disorders resulting from inappropriate levels of neurotransmitterrelease, inappropriate properties of neurotransmitter receptors, and/orinappropriate interaction between neurotransmitters and neurotransmitterreceptors). Several CNS disorders can be attributed to a deficiency ofcholine, dopamine, norepinephrine and/or serotonin.

Examples of CNS disorders that can be treated in accordance with thepresent invention include pre-senile dementia (early onset Alzheimer'sdisease), senile dementia (dementia of the Alzheimer's type), Lewy Bodydementia, micro-infarct dementia, AIDS-related dementia, HIV-dementia,multiple cerebral infarcts, Parkinsonism including Parkinson's disease,Pick's disease, progressive supranuclear palsy, Huntington's chorea,tardive dyskinesia, hyperkinesia, mania, attention deficit disorder,anxiety, depression, dyslexia, schizophrenia depression,obsessive-compulsive disorders, Tourette's syndrome, mild cognitiveimpairment (MCI), age-associated memory impairment (AAMI), prematureamnesic and cognitive disorders which are age-related or a consequenceof alcoholism, or immunodeficiency syndrome, or are associated withvascular disorders, with genetic alterations (such as, for example,trisomy 21) or with attention deficiencies or learning deficiencies,acute or chronic neurodegenerative conditions such as amyotrophiclateral sclerosis, multiple sclerosis, peripheral neurotrophies, andcerebral or spinal traumas. In addition, the compounds can be used totreat nicotine addiction and/or other behavioral disorders related tosubstances that lead to dependency (e.g., alcohol, cocaine, heroin andopiates, psychostimulants, benzodiazepines and barbiturates).

Schizophrenia is an example of a CNS disorder that is particularlyamenable to treatment by modulating the α7 nAChR subtype. The compoundscan also be administered to improve cognition and/or provideneuroprotection, and these uses are also particularly amenable totreatment with compounds, such as the compounds of the presentinvention, that are specific for the α7 nAChR subtype.

The disorders can be treated and/or prevented by administering to apatient in need of treatment or prevention thereof an effectivetreatment or preventative amount of a compound that provides some degreeof prevention of the progression of a CNS disorder (i.e., providesprotective effects), ameliorating the symptoms of the disorder, andameliorating the recurrence of the disorder.

Anti-Inflammatory Uses

Excessive inflammation and tumor necrosis factor synthesis causemorbidity and even mortality in a variety of diseases. These diseasesinclude, but are not limited to, endotoxemia, sepsis, rheumatoidarthritis, and irritable bowel disease. The nervous system, primarilythrough the vagus nerve, is known to regulate the magnitude of theinnate immune response by inhibiting the release of macrophage tumornecrosis factor (TNF). This physiological mechanism is known as the“cholinergic anti-inflammatory pathway” (see, for example, Tracey, “Theinflammatory reflex,” Nature. 420:853-9 (2002)).

The nicotinic acetylcholine receptor α7 subunit is required foracetylcholine inhibition of macrophage TNF release, and also inhibitsrelease of other cytokines. Agonists (or, at elevated dosages, partialagonists) at the α7-specific receptor subtype can inhibit theTNF-modulated inflammatory response. Accordingly, those compoundsdescribed herein that are α7 agonists can be used to treat inflammatorydisorders characterized by excessive synthesis of TNF (See also Wang etal., “Nicotinic acetylcholine receptor α7 subunit is an essentialregulator of inflammation”, Nature, 421:384-8 (2003)).

Inflammatory conditions that can be treated or prevented byadministering the compounds described herein include, but are notlimited to, chronic and acute inflammation, psoriasis, gout, acutepseudogout, acute gouty arthritis, arthritis, rheumatoid arthritis,osteoarthritis, allograft rejection, chronic transplant rejection,asthma, atherosclerosis, mononuclear-phagocyte dependent lung injury,idiopathic pulmonary fibrosis, atopic dermatitis, chronic obstructivepulmonary disease, adult respiratory distress syndrome, acute chestsyndrome in sickle cell disease, inflammatory bowel disease, Crohn'sdisease, ulcerative colitis, acute cholangitis, aphteous stomatitis,glomerulonephritis, lupus nephritis, thrombosis, and graft vs. hostreaction.

Minimizing the Inflammatory Response Associated with Bacterial and/orViral Infection

Many bacterial and/or viral infections are associated with side effectsbrought on by the formation of toxins, and the body's natural responseto the bacteria or virus and/or the toxins. Examples of such bacterialinfections include anthrax, botulism, and sepsis. As discussed above,the body's response to infection often involves generating a significantamount of TNF and/or other cytokines. The over-expression of thesecytokines can result in significant injury, such as septic shock (whenthe bacteria is sepsis), endotoxic shock, urosepsis and toxic shocksyndrome.

Cytokine expression is mediated by the α7 nAChR, and can be inhibited byadministering agonists or partial agonists of these receptors. Thosecompounds described herein that are agonists or partial agonists ofthese receptors can therefore be used to minimize the inflammatoryresponse associated with bacterial infection, as well as viral andfungal infections. Certain of the compounds themselves may also haveantimicrobial properties.

These compounds can also be used as adjunct therapy in combination withexisting therapies to manage bacterial, viral and fungal infections,such as antibiotics, antivirals and antifungals. Antitoxins can also beused to bind to toxins produced by the infectious agents and allow thebound toxins to pass through the body without generating an inflammatoryresponse. Examples of antitoxins are disclosed, for example, in U.S.Pat. No. 6,310,043 to Bundle et al., incorporated herein by reference.Other agents effective against bacterial and other toxins can beeffective and their therapeutic effect can be complimented byco-administration with the compounds described herein.

Analgesic Uses

The compounds can be administered to treat and/or prevent pain,including neurologic, neuropathic and chronic pain. The analgesicactivity of compounds described herein can be demonstrated in models ofpersistent inflammatory pain and of neuropathic pain, performed asdescribed in U.S. Published Patent Application No. 20010056084 A1(Allgeier et al.) (e.g., mechanical hyperalgesia in the completeFreund's adjuvant rat model of inflammatory pain and mechanicalhyperalgesia in the mouse partial sciatic nerve ligation model ofneuropathic pain).

The analgesic effect is suitable for treating pain of various genesis oretiology, in particular in treating inflammatory pain and associatedhyperalgesia, neuropathic pain and associated hyperalgesia, chronic pain(e.g., severe chronic pain, post-operative pain and pain associated withvarious conditions including cancer, angina, renal or billiary colic,menstruation, migraine and gout). Inflammatory pain may be of diversegenesis, including arthritis and rheumatoid disease, teno-synovitis andvasculitis. Neuropathic pain includes trigeminal or herpetic neuralgia,diabetic neuropathy pain, causalgia, low back pain and deafferentationsyndromes such as brachial plexus avulsion.

Inhibition of Neovascularization

The α7 nAChR is also associated with neovascularization. Inhibition ofneovascularization, for example, by administering antagonists (or atcertain dosages, partial agonists) of the α7 nAChR can treat or preventconditions characterized by undesirable neovascularization orangiogenesis. Such conditions can include those characterized byinflammatory angiogenesis and/or ischemia-induced angiogenesis.Neovascularization associated with tumor growth can also be inhibited byadministering those compounds described herein that function asantagonists or partial agonists of α7 nAChR.

Specific antagonism of α7 nAChR-specific activity reduces the angiogenicresponse to inflammation, ischemia, and neoplasia. Guidance regardingappropriate animal model systems for evaluating the compounds describedherein can be found, for example, in Heeschen, C. et al., “A novelangiogenic pathway mediated by non-neuronal nicotinic acetylcholinereceptors,” J. Clin. Invest 110(4):527-36 (2002), incorporated herein byreference regarding disclosure of α7-specific inhibition of angiogenesisand cellular (in vitro) and animal modeling of angiogenic activityrelevant to human disease, especially the Lewis lung tumor model (invivo, in mice—see, in particular, pages 529, and 532-533).

Representative tumor types that can be treated using the compoundsdescribed herein include NSCLC, ovarian cancer, pancreatic cancer,breast carcinoma, colon carcinoma, rectum carcinoma, lung carcinoma,oropharynx carcinoma, hypopharynx carcinoma, esophagus carcinoma,stomach carcinoma, pancreas carcinoma, liver carcinoma, gallbladdercarcinoma, bile duct carcinoma, small intestine carcinoma, urinary tractcarcinoma, kidney carcinoma, bladder carcinoma, urothelium carcinoma,female genital tract carcinoma, cervix carcinoma, uterus carcinoma,ovarian carcinoma, choriocarcinoma, gestational trophoblastic disease,male genital tract carcinoma, prostate carcinoma, seminal vesiclescarcinoma, testes carcinoma, germ cell tumors, endocrine glandcarcinoma, thyroid carcinoma, adrenal carcinoma, pituitary glandcarcinoma, skin carcinoma, hemangiomas, melanomas, sarcomas, bone andsoft tissue sarcoma, Kaposi's sarcoma, tumors of the brain, tumors ofthe nerves, tumors of the eyes, tumors of the meninges, astrocytomas,gliomas, glioblastomas, retinoblastomas, neuromas, neuroblastomas,Schwannomas, meningiomas, solid tumors arising from hematopoieticmalignancies (such as leukemias, chloromas, plasmacytomas and theplaques and tumors of mycosis fungoides and cutaneous T-celllymphoma/leukemia), and solid tumors arising from lymphomas.

The compounds can also be administered in conjunction with other formsof anti-cancer treatment, including co-administration withantineoplastic antitumor agents such as cis-platin, adriamycin,daunomycin, and the like, and/or anti-VEGF (vascular endothelial growthfactor) agents, as such are known in the art.

The compounds can be administered in such a manner that they aretargeted to the tumor site. For example, the compounds can beadministered in microspheres, microparticles or liposomes conjugated tovarious antibodies that direct the microparticles to the tumor.Additionally, the compounds can be present in microspheres,microparticles or liposomes that are appropriately sized to pass throughthe arteries and veins, but lodge in capillary beds surrounding tumorsand administer the compounds locally to the tumor. Such drug deliverydevices are known in the art.

Other Disorders

In addition to treating CNS disorders, inflammatory disorders, andneovascular disorders, and inhibiting the pain response, the compoundscan be also used to prevent or treat certain other conditions, diseases,and disorders. Examples include autoimmune disorders such as Lupus,disorders associated with cytokine release, cachexia secondary toinfection (e.g., as occurs in AIDS, AIDS related complex and neoplasia),as well as those indications set forth in PCT WO 98/25619. The compoundscan also be administered to treat convulsions such as those that aresymptomatic of epilepsy, and to treat conditions such as syphillis andCreutzfeld-Jakob disease.

Diagnostic Uses

The compounds can be used in diagnostic compositions, such as probes,particularly when they are modified to include appropriate labels. Theprobes can be used, for example, to determine the relative number and/orfunction of specific receptors, particularly the α7 receptor subtype.The compounds of the present invention most preferably are labeled witha radioactive isotopic moiety such as ¹¹C, ¹⁸F, ⁷⁶Br, ¹²³I or ¹²⁵I, asdiscussed above.

The administered compounds can be detected using known detection methodsappropriate for the label used. Examples of detection methods includeposition emission topography (PET) and single-photon emission computedtomography (SPECT). The radiolabels described above are useful in PET(e.g., ¹¹C, ¹⁸F or ⁷⁶Br) and SPECT (e.g., ¹²³I) imaging, with half-livesof about 20.4 minutes for ¹¹C, about 109 minutes for ¹⁸F, about 13 hoursfor ¹²³I, and about 16 hours for ⁷⁶Br. A high specific activity isdesired to visualize the selected receptor subtypes at non-saturatingconcentrations. The administered doses typically are below the toxicrange and provide high contrast images. The compounds are expected to becapable of administration in non-toxic levels. Determination of dose iscarried out in a manner known to one skilled in the art of radiolabelimaging. See, for example, U.S. Pat. No. 5,969,144 to London et al.

The compounds can be administered using known techniques. See, forexample, U.S. Pat. No. 5,969,144 to London et al. The compounds can beadministered in formulation compositions that incorporate otheringredients, such as those types of ingredients that are useful informulating a diagnostic composition. Compounds useful in accordancewith carrying out the present invention most preferably are employed informs of high purity. See, U.S. Pat. No. 5,853,696 to Elmalch et al.

After the compounds are administered to a subject (e.g., a humansubject), the presence of that compound within the subject can be imagedand quantified by appropriate techniques in order to indicate thepresence, quantity, and functionality of selected nicotinic cholinergicreceptor subtypes. In addition to humans, the compounds can also beadministered to animals, such as mice, rats, dogs, and monkeys. SPECTand PET imaging can be carried out using any appropriate technique andapparatus. See Villemagne et al., In: Arneric et al. (Eds.) NeuronalNicotinic Receptors Pharmacology and Therapeutic Opportunities, 235-250(1998) and U.S. Pat. No. 5,853,696 to Elmalch et al. for a disclosure ofrepresentative imaging techniques.

The radiolabeled compounds bind with high affinity to selective nAChRsubtypes (e.g., α7) and preferably exhibit negligible non-specificbinding to other nicotinic cholinergic receptor subtypes (e.g., thosereceptor subtypes associated with muscle and ganglia). As such, thecompounds can be used as agents for noninvasive imaging of nicotiniccholinergic receptor subtypes within the body of a subject, particularlywithin the brain for diagnosis associated with a variety of CNS diseasesand disorders.

In one aspect, the diagnostic compositions can be used in a method todiagnose disease in a subject, such as a human patient. The methodinvolves administering to that patient a detectably labelled compound asdescribed herein, and detecting the binding of that compound to selectednicotinic receptor subtypes (e.g., α7 receptor subtype). Those skilledin the art of using diagnostic tools, such as PET and SPECT, can use theradiolabeled compounds described herein to diagnose a wide variety ofconditions and disorders, including conditions and disorders associatedwith dysfunction of the central and autonomic nervous systems. Suchdisorders include a wide variety of CNS diseases and disorders,including Alzheimer's disease, Parkinson's disease, and schizophrenia.These and other representative diseases and disorders that can beevaluated include those that are set forth in U.S. Pat. No. 5,952,339 toBencherif et al., the contents of which are hereby incorporated byreference.

In another aspect, the diagnostic compositions can be used in a methodto monitor selective nicotinic receptor subtypes of a subject, such as ahuman patient. The method involves administering a detectably labeledcompound as described herein to that patient and detecting the bindingof that compound to selected nicotinic receptor subtypes (e.g., the α7receptor subtype).

The following examples are provided to further illustrate the presentinvention, and should not be construed as limiting thereof.

IV. Synthetic Examples

The following synthetic examples are provided to illustrate the presentinvention and should not be construed as limiting the scope thereof. Inthese examples, all parts and percentages are by weight, unlessotherwise noted. Reaction yields are reported in mole percentage.

The first step in synthesizing the compounds of interest is tosynthesize 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one, asdescribed below:

2-((3-Pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one

Potassium hydroxide (56 g, 0.54 mole) was dissolved in methanol (420mL). 3-Quinuclidinone hydrochloride (75 g, 0.49 mole) was added and themixture was stirred for 30 min at ambient temperature.3-Pyridinecarboxaldehyde (58 g, 0.54 mole) was added and the mixturestirred for 16 h at ambient temperature. The reaction mixture becameyellow during this period, with solids caking on the walls of the flask.The solids were scraped from the walls and the chunks broken up. Withrapid stirring, water (390 mL) was added. When the solids dissolved, themixture was cooled at 4° C. overnight. The crystals were collected byfiltration, washed with water, and air dried to obtain 80 g of yellowsolid. A second crop (8 g) was obtained by concentration of the filtrateto ˜10% of its former volume and cooling at 4° C. overnight. Both cropswere sufficiently pure for further transformation (88 g, 82%).

2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one

2-((3-Pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one (20 g, 93mmol) was suspended in methanol (200 mL) and treated with 46 mL of 6NHCl. 10% Palladium on carbon (1.6 g) was added and the mixture wasshaken under 25 psi hydrogen for 16 h. The mixture was filtered throughCelite and solvent removed from the filtrate by rotary evaporation, togive crude 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-onehydrochloride as a white gum (20 g). This was treated with 2N NaOH (50mL) and chloroform (50 mL) and stirred for an hour. The chloroform layerwas separated and the aqueous phase was treated with 2N NaOH, enough toraise the pH to 10 (about 5 mL), and saturated aqueous NaCl (25 mL).This was extracted with chloroform (3×10 mL), and the combined extractswere dried (MgSO₄) and concentrated by rotary evaporation. The residue(18 g) was dissolved in warm ether (320 mL) and cooled to 4° C. Thewhite solid was filtered off, washed with a small portion of cold etherand air dried. Concentration of the filtrate to ˜10% of its formervolume and cooling at 4° C. produced a second crop. A combined yield 16g (79%) was obtained.

The 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one can then beused to produce the scaffolds from which the remaining examples weresynthesized. The synthesis of the three scaffolds and their separationinto individual enantiomers was accomplished by the followingprocedures.

Scaffold 1: 2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol

In accordance with the procedure reported by Warawa et al., J. Med.Chem. 17(5): 497 (1974), a 250 mL three-neck round bottom flask wasfitted with a Vigreux column and distilling head.2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one (3.00 g, 13.9mmol), isopropanol (165 mL), aluminum isopropoxide (10.4 g, 50.9 mmol)and four boiling chips were added to the flask. The mixture was slowlydistilled under nitrogen, the distillate being collected over a 3 hperiod. When the distillate no longer showed the presence of acetone (by2,4-dinitrophenylhydrazone formation), the distillation was stopped andthe reaction mixture cooled to ambient temperature. The volatiles wereremoved by rotary evaporation and the gelatinous residue was dilutedwith saturated aqueous NaCl (50 mL) and 50% aqueous NaOH (10 mL). Themixture was then extracted with chloroform (3×25 mL), and the extractswere combined, dried over MgSO₄, and concentrated by rotary evaporation.The resulting amber oil became a cream-colored solid (3.02 g, 99.7%yield) upon high vacuum treatment. GCMS analysis indicated that theproduct is a 93:7 mixture of diastereomers. That the cis relativeconfiguration of 2-[(pyridin-3-yl)methyl]quinuclidin-3-ol was the majordiastereomer was established by comparison of the 3-H chemical shiftwith corresponding chemical shifts of cis- andtrans-2-(arylmethyl)quinuclidin-3-ols (Warawa and Campbell, J. Org.Chem. 39(24): 3511 (1974)).

(R,R) and (S,S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol

A mixture of (cis)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol(1.97 g, 9.04 mmol), N,N-dicyclohexylcarbodiimide (3.73 g, 18.1 mmol),4-dimethylaminopyridine (55 mg, 0.40 mmol), (S)-2-methoxy-2-phenylaceticacid (3.00 g, 18.1 mmol), and anhydrous dichloromethane (125 mL) wasstirred at ambient temperature under nitrogen for 24 h. The precipitatedN,N-dicyclohexylurea was filtered from the reaction mixture and thefiltrate was extracted sequentially with water (200 mL), saturatedaqueous NaHCO₃ (200 mL) and saturated aqueous NaCl (200 mL). The organiclayer was dried (MgSO₄), filtered and concentrated to give a dark orangeoil (4.45 g). A portion (4.2 g) of this diastereomeric mixture wasdissolved in acetonitrile (8.4 mL) and separated, in portions, bypreparative HPLC, using 90:10:0.1 acetonitrile/water/trifluoroaceticacid as eluent. The diastereomers exhibited retention times of 3.8 minand 4.5 min. The corresponding fractions from the various injectionswere combined and concentrated to yield 1.1 g (56% yield) and 0.70 g(36% yield), respectively, as clear, colorless oils. LCMS analysis ofthe solvent-free esters confirmed the efficiency of their separation,showing diastereomeric purities of 92% (for the 3.8 min fraction) and95% (for the 4.5 min fraction).

In separate flasks, portions (0.175 g, 0.477 mmol) of each of thediastereomers were dissolved in methanol (2.5 mL) and treated withsolutions of KOH (0.20 g, 3.6 mmol) in methanol (3 mL). These mixtureswere stirred overnight at ambient temperature. The methanol was removedby evaporation, and the residues were diluted with a mixture ofsaturated aqueous NaCl (2 mL) and 50% NaOH (1 mL) and then extractedwith chloroform (3×5 mL). For each of the hydrolyses, the organic layerswere combined, dried (MgSO₄), filtered, and concentrated. This gave0.061 g (59% yield) of the enantiomer derived from the 3.8 min peak and0.056 g (54% yield) of the enantiomer derived from the 4.5 min peak.Both were clear, colorless oils.

Scaffold 2: 3-Amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane

To a stirred solution of2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one (3.00 g, 13.9mmol) in dry methanol (20 mL), under nitrogen, was added a 1 M solutionof ZnCl₂ in ether (2.78 mL, 2.78 mmol). After stirring at ambienttemperature for 30 min, this mixture was treated with solid ammoniumformate (10.4 g, 167 mmol). After stirring another hour at ambienttemperature, solid sodium cyanoborohydride (1.75 g, 27.8 mmol) was addedin portions. The reaction was then stirred at ambient temperatureovernight and terminated by addition of water (˜5 mL). The quenchedreaction was partitioned between 5 M NaOH (10 mL) and chloroform (20mL). The aqueous layer was extracted with chloroform (20 mL), andcombined organic layers were dried (Na₂SO₄), filtered and concentrated.This left 2.97 g of yellow gum. GC/MS analysis indicated that theproduct was a 90:10 mixture of the cis and trans amines, along with atrace of the corresponding alcohol (98% mass recovery).

(R,R) and(S,S)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane

Di-p-toluoyl-D-tartaric acid (5.33 g, 13.8 mmol) was added to a stirredsolution of crude3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (6.00 g, 27.6mmol of 9:1 cis/trans) in methanol (20 mL). After complete dissolution,the clear solution was then concentrated to a solid mass by rotaryevaporation. The solid was dissolved in a minimum amount of boilingmethanol (˜5 mL). The solution was cooled slowly, first to ambienttemperature (1 h), then for ˜4 h at 5° C. and finally at −5° C.overnight. The precipitated salt was collected by suction filtration andrecrystallized from 5 mL of methanol. Drying left 1.4 g of white solid,which was partitioned between chloroform (5 mL) and 2 M NaOH (5 mL). Thechloroform layer and a 5 mL chloroform extract of the aqueous layer werecombined, dried (Na₂SO₄) and concentrated to give a colorless oil (0.434g). The enantiomeric purity of this free base was determined byconversion of a portion into its N-(tert-butoxycarbonyl)-L-prolinamide,which was then analyzed for diastereomeric purity (98%) using LCMS.

The mother liquor from the initial crystallization was made basic (˜pH11) with 2 M NaOH and extracted twice with chloroform (10 mL). Thechloroform extracts were dried (Na₂SO₄) and concentrated to give an oil.This amine (3.00 g, 13.8 mmol) was dissolved in methanol (10 mL) andtreated with di-p-toluoyl-L-tartaric acid (2.76 g, 6.90 mmol). Themixture was warmed to aid dissolution and then cooled slowly to −5° C.,where it remained overnight. The precipitate was collected by suctionfiltration, recrystallized and dried. This left 1.05 g of white solid.The salt was converted into the free base as described above for theother isomer (yield=0.364 g), and the enantiomeric purity (97%) wasassessed using the prolinaminde method, described above.

Scaffold 3:3-Aminomethyl-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane

2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one (2.16 g, 0.01mol), methylamine (25 mL, 0.05 mol) and zinc chloride (5 mL, 0.005 mol)were added to dry methanol (30 mL) and stirred at room temperature for30 min. Then, sodium cyanoborohydride (30 mL, 1.0M in THF) was addedcarefully and the mixture stirred at room temperature for 48 h. Themixture was adjusted to pH 10 using 2N potassium hydroxide and then thesolvent was removed by rotary evaporation. The residue was extractedwith chloroform (3×50 mL), dried (MgSO₄), filtered and concentrated byrotary evaporation to yield the crude desired amine as a light yellowoil (2.40 g, 83% yield). The product was taken on to the next stepwithout further purification.

The following example describes the synthesis of various2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl N-arylcarbamates,which are built upon Scaffold 1. Table 1 shows a list of variouscompounds within this example that were synthesized.

EXAMPLE 1 2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-ylN-arylcarbamates

Various aryl isocyanates (0.2 mmol) were combined with2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol (0.2 mmol) inanhydrous toluene (1 mL). The reaction mixtures were heated at 100° C.for 3 h and concentrated by centrifugal evaporation. The residues weredissolved in DMF (0.5 mL) and purified by HPLC on a C18 silica gelcolumn, using acetonitrile/water gradients containing 0.05%trifluoroacetic acid as eluent. Compounds were isolated astrifluoroacetate salts and characterized by LCMS. All compoundsexhibited appropriate molecular ions and fragmentation patterns. Thoseof 90% or greater purity were submitted for biological assessment.Selected compounds were analyzed by NMR spectroscopy, which confirmedtheir structural assignments.

TABLE 1 Calc. LCMS Compound FB Mass # Compound Name Mass (MH⁺) 12-((3-pyridinyl)methyl)-1- 416.321 418.17 azabicyclo[2.2.2]oct-3-ylN-(4- (⁸¹Br) bromophenyl)carbamate 2 2-((3-pyridinyl)methyl)-1- 337.425338.34 azabicyclo[2.2.2]oct-3-yl N- phenylcarbamate 32-((3-pyridinyl)methyl)-1- 355.416 356.30 azabicyclo[2.2.2]oct-3-ylN-(4- fluorophenyl)carbamate 4 2-((3-pyridinyl)methyl)-1- 367.452 368.4 azabicyclo[2.2.2]oct-3-yl N-(4- methoxyphenyl)carbamate 52-((3-pyridinyl)methyl)-1- 383.516 384.29 azabicyclo[2.2.2]oct-3-ylN-(4- methylthiophenyl)carbamate 6 Levorotatory 2-((3-pyridinyl)methyl)-337.425 338.36 1-azabicyclo[2.2.2]oct-3-yl N- phenylcarbamate 7Dextrorotatory 2-((3-pyridinyl) 337.425 338.37methyl)-1-azabicyclo[2.2.2]oct-3-yl N- phenylcarbamate

Scale-up of 2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl(N-(4-bromophenyl)carbamate hydrochloride (Compound 1)

2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-ol (0.218 g, 1.00mmol) and p-bromophenylisocyanate (0.198 g, 1.00 mmol) were suspended inanhydrous toluene (2 mL) and heated at 180° C. for 5 min (microwavereactor). The volatiles were removed by rotary evaporation, and theresidue was purified by flash (silica gel) column chromatography, usingfirst chloroform/hexane/methanol/ammonia (68:25:7:1) and thenchloroform/methanol/ammonia (90:10:1) as eluent. Concentration ofselected fractions gave 0.260 g (62.5% yield) of colorless oil, whichformed a waxy white solid upon standing at ambient temperature. NMRanalysis confirmed that the material was predominantly the cisdiastereomer. This material was dissolved in 4 M HCl in dioxane andconcentrated to dryness, leaving a hygroscopic white solid.

The following example describes the synthesis of variousN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)arylcarboxamides,which are built upon Scaffold 2. Table 2 shows a list of variouscompounds within this example that were synthesized.

EXAMPLE 2N-(2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)arylcarboxamides

Diphenylchlorophosphate (0.3 mmol) was added drop-wise to solutions ofvarious arylcarboxylic acids (0.3 mmol) and triethylamine (0.3 mmol) indry dichloromethane (1 mL). After stirring at ambient temperature for 1h, a solution of3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (0.3 mmol) andtriethylamine (0.6 mmol) in dry dichloromethane (0.5 mL) was added toeach of the mixed anhydride solutions. The reaction mixtures werestirred overnight at ambient temperature, then diluted with chloroform(2 mL) and washed with 5 M NaOH (2 mL). The organic layers wereconcentrated under reduced pressure, and the residues were dissolved inmethanol (0.5 ml) and purified by HPLC on a C18 silica gel column, usingacetonitrile/water gradients containing 0.05% trifluoroacetic acid aseluent. Compounds were isolated as trifluoroacetate salts andcharacterized by LCMS. All compounds exhibited appropriate molecularions and fragmentation patterns. Those of 90% or greater purity weresubmitted for biological assessment. Selected compounds were analyzed byNMR spectroscopy, which confirmed their structural assignments.

TABLE 2 Calc. LCMS Compound FB Mass # Compound Name Mass (MH⁺) 8N-(2-((3-pyridinyl)methyl)-1- 339.416 340.31azabicyclo[2.2.2]oct-3-yl)-4- fluorobenzamide 9N-(2-((3-pyridinyl)methyl)-1- 361.448 362.33azabicyclo[2.2.2]oct-3-yl)benzofuran- 2-carboxamide 10N-(2-((3-pyridinyl)methyl)-1- 400.322 402.25azabicyclo[2.2.2]oct-3-yl)-4- (⁸¹Br) bromobenzamide 11N-(2-((3-pyridinyl)methyl)-1- 429.589 430.30azabicyclo[2.2.2]oct-3-yl)-4- phenylthiobenzamide 12N-(2-((3-pyridinyl)methyl)-1- 373.543 374.32azabicyclo[2.2.2]oct-3-yl)-5- methylthiothiophene-2-carboxamide 13N-(2-((3-pyridinyl)methyl)-1- 321.426 322.35azabicyclo[2.2.2]oct-3-yl)benzamide 14 N-(2-((3-pyridinyl)methyl)-1-351.452 352.37 azabicyclo[2.2.2]oct-3-yl)-3- methoxybenzamide 15N-(2-((3-pyridinyl)methyl)-1- 400.322 402.24azabicyclo[2.2.2]oct-3-yl)-3- (⁸¹Br) bromobenzamide

Scale-up ofN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide(Compound 9)

Diphenylchlorophosphate (0.35 mL, 0.46 g, 1.69 mmol) was added drop-wiseto a solution of the arylcarboxylic acid (0.280 g, 1.73 mmol) andtriethylamine (0.24 mL, 0.17 g, 1.7 mmol) in dry dichloromethane (5 mL).After stirring at ambient temperature for 30 min, a solution of3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (0.337 g, 1.55mmol) and triethylamine (0.24 mL, 0.17 g, 1.7 mmol) in drydichloromethane (5 mL) was added. The reaction mixture was stirredovernight at ambient temperature, and then treated with 10% NaOH (1 mL).The biphasic mixture was separated by phase filtration, and the organiclayer was concentrated on a Genevac centrifugal evaporator. The residuewas dissolved in methanol (6 mL) and purified by HPLC on a C18 silicagel column, using an acetonitrile/water gradient containing 0.05%trifluoroacetic acid as eluent. Concentration of selected fractions gave0.310 g (42% yield) of a white powder (95% pure by GCMS).

The following example describes the synthesis of variousN-Aryl-N′-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)ureas,which are built upon Scaffolds 2 and 3. Table 3 shows a list of variouscompounds within this example that were synthesized.

EXAMPLE 3N-Aryl-N′-(2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)ureas

Various arylisocyanates (0.3 mmol) were stirred with3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (0.3 mmol) inchloroform solution (1 mL) for 48 h at ambient temperature. The reactionmixtures were concentrated under reduced pressure, and the residues weredissolved in methanol (0.5 mL) and purified by HPLC on a C18 silica gelcolumn, using acetonitrile/water gradients containing 0.05%trifluoroacetic acid as eluent. Compounds were isolated astrifluoroacetate salts and characterized by LCMS. All compoundsexhibited appropriate molecular ions and fragmentation patterns. Thoseof 90% or greater purity were submitted for biological assessment.Selected compounds were analyzed by NMR spectroscopy, which confirmedtheir structural assignments.

Compounds possessing a methyl group on the nitrogen adjacent to thequinuclidine ring were prepared, by the same procedure as describedabove for unsubstituted ureas, using Scaffold 3.

TABLE 3 Calc. LCMS Compound FB Mass # Compound Name Mass (MH⁺) 16N-phenyl-N′-(2-((3-pyridinyl)methyl)- 336.440 337.391-azabicyclo[2.2.2]oct-3-yl)urea 17 N-(4-phenoxyphenyl)-N′-(2-((3-428.539 429.36 pyridinyl)methyl)-1- azabicyclo[2.2.2]oct-3-yl)urea 18N-(4-methylthiophenyl)-N′-(2-((3- 382.532 383.34 pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea 19 N-(3-fluorophenyl)-N′-(2-((3- 354.431355.35 pyridinyl)methyl)-1- azabicyclo[2.2.2]oct-3-yl)urea 20N-(4-bromophenyl)-N′-(2-((3- 415.337 417.22 pyridinyl)methyl)-1- (⁸¹Br)azabicyclo[2.2.2]oct-3-yl)urea 21 N-(2-methoxyphenyl)-N′-(2-((3- 366.467367.34 pyridinyl)methyl)-1- azabicyclo[2.2.2]oct-3-yl)urea 22N-(2,4-dimethoxyphenyl)-N′-(2-((3- 396.493 397.37 pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea 23 N-(3,4-dichlorophenyl)-N′-(2-((3-405.331 405.23 pyridinyl)methyl)-1- (³⁵CI)azabicyclo[2.2.2]oct-3-yl)urea 24 N-(4-methoxyphenyl)-N′-(2-((3- 366.467367.34 pyridinyl)methyl)-1- azabicyclo[2.2.2]oct-3-yl)urea 25N-(4-dimethylaminophenyl)-N′-(2- 379.509 380.40 ((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)urea 26 N-phenyl-N′-methyl-N′-(2-((3- 350.468351.42 pyridinyl)methyl)-1- azabicyclo[2.2.2]oct-3-yl)urea 27N-(4-bromophenyl)-N′-methyl-N′-(2- 429.364 431.26((3-pyridinyl)methyl)-1- (⁸¹Br) azabicyclo[2.2.2]oct-3-yl)urea

The following example describes the synthesis of variousN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)cinnamamides,which are built upon Scaffold 2. Table 4 shows a list of variouscompounds within this example that were synthesized.

EXAMPLE 4N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)cinnamamides

To a stirring solution of triethylamine (25 mL) in dry dichloromethane(0.5 mL) was added3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (0.040 g, 0.18mmol). The mixture was cooled to 0° C. and stirred for 30 min. Thenvarious cinnamoyl chlorides (0.18 mmol) were added and the mixturesallowed to stir at 0° C. for 30 min, then warm to room temperature andstir overnight. The mixtures were partitioned between saturated NaHCO₃solution (25 mL) and chloroform (25 mL). The organic layers were washedwith brine (3×5 mL), dried (Na₂SO₄) and concentrated by rotaryevaporation. The residues were dissolved in methanol (0.5 mL) andpurified by HPLC on a C18 silica gel column, using acetonitrile/watergradients containing 0.05% trifluoroacetic acid as eluent. Compoundswere isolated as trifluoroacetate salts and characterized by LCMS. Allcompounds exhibited appropriate molecular ions and fragmentationpatterns. Those of 90% or greater purity were submitted for biologicalassessment. Selected compounds were analyzed by NMR spectroscopy, whichconfirmed their structural assignments.

TABLE 4 Calc. LCMS Compound FB Mass # Compound Name Mass (MH⁺) 28N-(2-((3-pyridinyl)methyl)-1- 347.464 348.16azabicyclo[2.2.2]oct-3-yl)3- phenylprop-2-enamide 29N-(2-((3-pyridinyl)methyl)-1- 381.909 382.26azabicyclo[2.2.2]oct-3-yl)-3- (4-chlorophenyl)prop-2-enamide 30N-(2-((3-pyridinyl)methyl)-1- 426.360 428.20azabicyclo[2.2.2]oct-3-yl)-3- (⁸¹Br) (4-bromophenyl)prop-2-enamide 31N-(2-((3-pyridinyl)methyl)-1- 363.463 364.35azabicyclo[2.2.2]oct-3-yl)-3- (3-hydroxyphenyl)prop-2-enamide 32N-(2-((3-pyridinyl)methyl)-1- 377.491 378.32azabicyclo[2.2.2]oct-3-yl)-3- (3-methoxyphenyl)prop-2-enamide 33N-(2-((3-pyridinyl)methyl)-1- 365.454 366.33azabicyclo[2.2.2]oct-3-yl)-3- (2-fluorophenyl)prop-2-enamide 34N-(2-((3-pyridinyl)methyl)-1- 363.463 364.35azabicyclo[2.2.2]oct-3-yl)-3- (2-hydroxyphenyl)prop-2-enamideV. Biological Assays

EXAMPLE 5 Radioligand Binding at CNS nAChRs

α4β2 nAChR Subtype

Rats (female, Sprague-Dawley), weighing 150-250 g, were maintained on a12 h light/dark cycle and were allowed free access to water and foodsupplied by PMI Nutrition International, Inc. Animals were anesthetizedwith 70% CO₂, then decapitated. Brains were removed and placed on anice-cold platform. The cerebral cortex was removed and placed in 20volumes (weight:volume) of ice-cold preparative buffer (137 mM NaCl,10.7 mM KCl, 5.8 mM KH₂PO₄, 8 mM Na₂HPO₄, 20 mM HEPES (free acid), 5 mMiodoacetamide, 1.6 mM EDTA, pH 7.4); PMSF, dissolved in methanol to afinal concentration of 100 μM, was added and the suspension washomogenized by Polytron. The homogenate was centrifuged at 18,000×g for20 min at 4° C. and the resulting pellet was re-suspended in 20 volumesof ice-cold water. After 60 min incubation on ice, a new pellet wascollected by centrifugation at 18,000×g for 20 min at 4° C. The finalpellet was re-suspended in 10 volumes of buffer and stored at −20° C. Onthe day of the assay, tissue was thawed, centrifuged at 18,000×g for 20min, and then re-suspended in ice-cold PBS (Dulbecco's PhosphateBuffered Saline, 138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1 mMNa₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH 7.4) to afinal concentration of approximately 4 mg protein/mL. Protein wasdetermined by the method of Lowry et al., J. Biol. Chem. 193: 265(1951), using bovine serum albumin as the standard.

The binding of [³H]nicotine was measured using a modification of themethods of Romano et al., Science 210: 647 (1980) and Marks et al., Mol.Pharmacol. 30: 427 (1986). The [³H]nicotine (Specific Activity=81.5Ci/mmol) was obtained from NEN Research Products. The binding of[³H]nicotine was measured using a 3 h incubation at 4° C. Incubationswere conducted in 48-well micro-titre plates and contained about 400 μgof protein per well in a final incubation volume of 300 μL. Theincubation buffer was PBS and the final concentration of [³H]nicotinewas 5 nM. The binding reaction was terminated by filtration of theprotein containing bound ligand onto glass fiber filters (GF/B, Brandel)using a Brandel Tissue Harvester at 4° C. Filters were soaked inde-ionized water containing 0.33% polyethyleneimine to reducenon-specific binding. Each filter was washed with ice-cold buffer (3×1mL). Non-specific binding was determined by inclusion of 10 μMnon-radioactive L-nicotine (Acros Organics) in selected wells.

The inhibition of [³H]nicotine binding by test compounds was determinedby including seven different concentrations of the test compound inselected wells. Each concentration was replicated in triplicate. IC₅₀values were estimated as the concentration of compound that inhibited 50percent of specific [³H]nicotine binding. Inhibition constants (Kivalues), reported in nM, were calculated from the IC₅₀ values using themethod of Cheng et al., Biochem. Pharmacol. 22: 3099 (1973).

For initial screening, a single concentration of test compounds wastested in the above assay format with the following modifications. Thebinding of [³H]epibatidine was measured. The [³H]epibatidine (SpecificActivity=48 Ci/mmol) was obtained from NEN Research Products. Thebinding of [³H]epibatidine was measured using a 2 h incubation at 21° C.(room temperature). Incubations were conducted in 96-well MilliporeMultiscreen (MAFB) plates containing about 200 μg of protein per well ina final incubation volume of 150 μL. The incubation buffer was PBS andthe final concentration of [³H]epibatidine was 0.3 nM. The bindingreaction was terminated by filtration of the protein containing boundligand onto the glass fiber filter base of the Multiscreen plates.Filters were soaked in de-ionized water containing 0.33%polyethyleneimine to reduce non-specific binding. Each filter was washedwith ice-cold buffer (3×0.25 mL). Non-specific binding was determined byinclusion of 10 μM non-radioactive L-nicotine (Acros Organics) inselected wells. The single concentration of test compound was 5 μM andtesting was performed in triplicate. ‘Active’ compounds were defined ascompounds that inhibited the binding of [³H]epibatidine to the receptorby at least 50% compared with the binding of [³H]epibatidine in theabsence of competitor. For those compounds found to be active in thesingle point screen, the inhibition constants (Ki values) weredetermined as described in the previous paragraphs of this section.

α7 nAChR Subtype

Rats (female, Sprague-Dawley), weighing 150-250 g, were maintained on a12 h light/dark cycle and were allowed free access to water and foodsupplied by PMI Nutrition International, Inc. Animals were anesthetizedwith 70% CO₂, then decapitated. Brains were removed and placed on anice-cold platform. The hippocampus was removed and placed in 10 volumes(weight:volume) of ice-cold preparative buffer (137 mM NaCl, 10.7 mMKCl, 5.8 mM KH₂PO₄, 8 mM Na₂HPO₄, 20 mM HEPES (free acid), 5 mMiodoacetamide, 1.6 mM EDTA, pH 7.4); PMSF, dissolved in methanol to afinal concentration of 100 μM, was added and the tissue suspension washomogenized by Polytron. The homogenate was centrifuged at 18,000×g for20 min at 4° C. and the resulting pellet was re-suspended in 10 volumesof ice-cold water. After 60 min incubation on ice, a new pellet wascollected by centrifugation at 18,000×g for 20 min at 4° C. The finalpellet was re-suspended in 10 volumes of buffer and stored at −20° C. Onthe day of the assay, tissue was thawed, centrifuged at 18,000×g for 20min, and then re-suspended in ice-cold PBS (Dulbecco's PhosphateBuffered Saline, 138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1 mMNa₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH 7.4) to afinal concentration of approximately 2 mg protein/mL. Protein wasdetermined by the method of Lowry et al., J. Biol. Chem. 193: 265(1951), using bovine serum albumin as the standard.

The binding of [³H]MLA was measured using a modification of the methodsof Davies et al., Neuropharmacol. 38: 679 (1999). [³H]MLA (SpecificActivity=25-35 Ci/mmol) was obtained from Tocris. The binding of [³H]MLAwas determined using a 2 h incubation at 21° C. Incubations wereconducted in 48-well micro-titre plates and contained about 200 μg ofprotein per well in a final incubation volume of 300 μL. The incubationbuffer was PBS and the final concentration of [³H]MLA was 5 nM. Thebinding reaction was terminated by filtration of the protein containingbound ligand onto glass fiber filters (GF/B, Brandel) using a BrandelTissue Harvester at room temperature. Filters were soaked in de-ionizedwater containing 0.33% polyethyleneimine to reduce non-specific binding.Each filter was washed with PBS (3×1 mL) at room temperature.Non-specific binding was determined by inclusion of 50 μMnon-radioactive MLA in selected wells.

The inhibition of [³H]MLA binding by test compounds was determined byincluding seven different concentrations of the test compound inselected wells. Each concentration was replicated in triplicate. IC₅₀values were estimated as the concentration of compound that inhibited 50percent of specific [³H]MLA binding. Inhibition constants (Ki values),reported in nM, were calculated from the IC₅₀ values using the method ofCheng et al., Biochem. Pharmacol. 22: 3099-3108 (1973).

For initial screening, a single concentration of test compounds wastested in the above assay format with the following modifications.Incubations were conducted in 96-well plates in a final incubationvolume of 150 μL. Once the binding reaction was terminated by filtrationonto glass fiber filters, the filters were washed four times withapproximately 250 μL of PBS at room temperature. Non-specific bindingwas determined by inclusion of 10 μM non-radioactive MLA in selectedwells. The single concentration of test compound was 5 μM and testingwas performed in triplicate. ‘Active’ compounds were defined ascompounds that inhibited the binding of [³H]MLA to the receptor by atleast 50% compared with the binding of [³H]MLA in the absence ofcompetitor. For those compounds found to be active in the single pointscreen, the inhibition constants (Ki values) were determined asdescribed in the previous paragraphs of this section.

Determination of Dopamine Release

Dopamine release was measured using striatal synaptosomes obtained fromrat brain, according to the procedures set forth by Rapier et al., J.Neurochem. 54: 937 (1990). Rats (female, Sprague-Dawley), weighing150-250 g, were maintained on a 12 h light/dark cycle and were allowedfree access to water and food supplied by PMI Nutrition International,Inc. Animals were anesthetized with 70% CO₂, then decapitated. Thebrains were quickly removed and the striata dissected. Striatal tissuefrom each of 2 rats was pooled and homogenized in ice-cold 0.32 Msucrose (5 mL) containing 5 mM HEPES, pH 7.4, using a glass/glasshomogenizer. The tissue was then centrifuged at 1,000×g for 10 min. Thepellet was discarded and the supernatant was centrifuged at 12,000×g for20 min. The resulting pellet was re-suspended in perfusion buffercontaining monoamine oxidase inhibitors (128 mM NaCl, 1.2 mM KH₂PO₄, 2.4mM KCl, 3.2 mM CaCl₂, 1.2 mM MgSO₄, 25 mM HEPES, 1 mM ascorbic acid,0.02 mM pargyline HCl and 10 mM glucose, pH 7.4) and centrifuged for 15min at 25,000×g. The final pellet was resuspended in perfusion buffer(1.4 mL) for immediate use.

The synaptosomal suspension was incubated for 10 min at 37° C. torestore metabolic activity. [³H]Dopamine ([³H]DA, specific activity=28.0Ci/mmol, NEN Research Products) was added at a final concentration of0.1 μM and the suspension was incubated at 37° C. for another 10 min.Aliquots of tissue (50 μL) and perfusion buffer (100 μL) were loadedinto the suprafusion chambers of a Brandel Suprafusion System (series2500, Gaithersburg, Md.). Perfusion buffer (room temperature) was pumpedinto the chambers at a rate of 3 mL/min for a wash period of 8 min. Testcompound (10 μM) or nicotine (10 μM) was then applied in the perfusionstream for 40 sec. Fractions (12 sec each) were continuously collectedfrom each chamber throughout the experiment to capture basal release andagonist-induced peak release and to re-establish the baseline after theagonist application. The perfusate was collected directly intoscintillation vials, to which scintillation fluid was added. [³H]DAreleased was quantified by scintillation counting. For each chamber, theintegrated area of the peak was normalized to its baseline.

Release was expressed as a percentage of release obtained with an equalconcentration of L-nicotine. Within each assay, each test compound wasreplicated using 2-3 chambers; replicates were averaged. Whenappropriate, dose-response curves of test compound were determined. Themaximal activation for individual compounds (Emax) was determined as apercentage of the maximal activation induced by L-nicotine. The compoundconcentration resulting in half maximal activation (EC₅₀) of specificion flux was also defined.

EXAMPLE 6 Selectivity vs. Peripheral nAChRs

Interaction at the Human Muscle nAChR Subtype

Activation of muscle-type nAChRs was established on the human clonalline TE671/RD, which is derived from an embryonal rhabdomyosarcoma(Stratton et al., Carcinogen 10: 899 (1989)). These cells expressreceptors that have pharmacological (Lukas, J. Pharmacol. Exp. Ther.251: 175 (1989)), electrophysiological (Oswald et al., Neurosci. Lett.96: 207 (1989)), and molecular biological profiles (Luther et al., J.Neurosci. 9: 1082 (1989)) similar to the muscle-type nAChR.

TE671/RD cells were maintained in proliferative growth phase accordingto routine protocols (Bencherif et al., Mol. Cell. Neurosci. 2: 52(1991) and Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946 (1991)).Cells were cultured in Dulbecco's modified Eagle's medium (Gibco/BRL)with 10% horse serum (Gibco/BRL), 5% fetal bovine serum (HyClone, LoganUtah), 1 mM sodium pyruvate, 4 mM L-Glutamine, and 50,000 unitspenicillin-streptomycin (Irvine Scientific). When cells were 80%confluent, they were plated to 6 well polystyrene plates (Costar).Experiments were conducted when the cells reached 100% confluency.

Nicotinic acetylcholine receptor (nAChR) function was assayed using⁸⁶Rb⁺ efflux according to the method described by Lukas et al., Anal.Biochem. 175: 212 (1988). On the day of the experiment, growth media wasgently removed from the well and growth media containing ⁸⁶Rubidiumchloride (10⁶ μCi/mL) was added to each well. Cells were incubated at37° C. for a minimum of 3 h. After the loading period, excess ⁸⁶Rb⁺ wasremoved and the cells were washed twice with label-free Dulbecco'sphosphate buffered saline (138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1mM Na₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH. 7.4),taking care not to disturb the cells. Next, cells were exposed to either100 μM of test compound, 100 μM of L-nicotine (Acros Organics) or bufferalone for 4 min. Following the exposure period, the supernatantcontaining the released ⁸⁶Rb⁺ was removed and transferred toscintillation vials. Scintillation fluid was added and releasedradioactivity was measured by liquid scintillation counting.

Within each assay, each point had 2 replicates, which were averaged. Theamount of ⁸⁶Rb⁺ release was compared to both a positive control (100 μML-nicotine) and a negative control (buffer alone) to determine thepercent release relative to that of L-nicotine.

When appropriate, dose-response curves of test compound were determined.The maximal activation for individual compounds (Emax) was determined asa percentage of the maximal activation induced by L-nicotine. Thecompound concentration resulting in half maximal activation (EC₅₀) ofspecific ion flux was also determined.

Interaction at the Rat Ganglionic nAChR Subtype

Activation of rat ganglion nAChRs was established on thepheochromocytoma clonal line PC12, which is a continuous clonal cellline of neural crest origin, derived from a tumor of the rat adrenalmedulla. These cells express ganglion-like nAChR s (see Whiting et al.,Nature 327: 515 (1987); Lukas, J. Pharmacol. Exp. Ther. 251: 175 (1989);Whiting et al., Mol. Brain. Res. 10: 61 (1990)).

Rat PC12 cells were maintained in proliferative growth phase accordingto routine protocols (Bencherif et al., Mol. Cell. Neurosci. 2: 52(1991) and Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946 (1991)).Cells were cultured in Dulbecco's modified Eagle's medium (Gibco/BRL)with 10% horse serum (Gibco/BRL), 5% fetal bovine serum (HyClone, LoganUtah), 1 mM sodium pyruvate, 4 mM L-Glutamine, and 50,000 unitspenicillin-streptomycin (Irvine Scientific). When cells were 80%confluent, they were plated to 6 well Nunc plates (Nunclon) and coatedwith 0.03% poly-L-lysine (Sigma, dissolved in 100 mM boric acid).Experiments were conducted when the cells reached 80% confluency.

Nicotinic acetylcholine receptor (nAChR) function was assayed using⁸⁶Rb⁺ efflux according to a method described by Lukas et al., Anal.Biochem. 175: 212 (1988). On the day of the experiment, growth media wasgently removed from the well and growth media containing ⁸⁶Rubidiumchloride (10⁶ μCi/mL) was added to each well. Cells were incubated at37° C. for a minimum of 3 h. After the loading period, excess ⁸⁶Rb⁺ wasremoved and the cells were washed twice with label-free Dulbecco'sphosphate buffered saline (138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1mM Na₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH. 7.4),taking care not to disturb the cells. Next, cells were exposed to either100 μM of test compound, 100 μM of nicotine or buffer alone for 4 min.Following the exposure period, the supernatant containing the released⁸⁶Rb⁺ was removed and transferred to scintillation vials. Scintillationfluid was added and released radioactivity was measured by liquidscintillation counting

Within each assay, each point had 2 replicates, which were averaged. Theamount of ⁸⁶Rb⁺ release was compared to both a positive control (100 μMnicotine) and a negative control (buffer alone) to determine the percentrelease relative to that of L-nicotine.

When appropriate, dose-response curves of test compound were determined.The maximal activation for individual compounds (Emax) was determined asa percentage of the maximal activation induced by L-nicotine. Thecompound concentration resulting in half maximal activation (EC₅₀) ofspecific ion flux was also determined.

Interaction at the Human Ganglionic nAChR Subtype

The cell line SH-SY5Y is a continuous line derived by sequentialsubcloning of the parental cell line, SK-N-SH, which was originallyobtained from a human peripheral neuroblastoma. SH-SY5Y cells express aganglion-like nAChR (Lukas et al., Mol. Cell. Neurosci. 4: 1 (1993)).

Human SH-SY5Y cells were maintained in proliferative growth phaseaccording to routine protocols (Bencherif et al., Mol. Cell. Neurosci.2: 52 (1991) and Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946(1991)). Cells were cultured in Dulbecco's modified Eagle's medium(Gibco/BRL) with 10% horse serum (Gibco/BRL), 5% fetal bovine serum(HyClone, Logan Utah), 1 mM sodium pyruvate, 4 mM L-Glutamine, and50,000 units penicillin-streptomycin (Irvine Scientific). When cellswere 80% confluent, they were plated to 6 well polystyrene plates(Costar). Experiments were conducted when the cells reached 100%confluency.

Nicotinic acetylcholine receptor (nAChR) function was assayed using⁸⁶Rb⁺ efflux according to a method described by Lukas et al., Anal.Biochem. 175: 212 (1988). On the day of the experiment, growth media wasgently removed from the well and growth media containing ⁸⁶Rubidiumchloride (10⁶ μCi/mL) was added to each well. Cells were incubated at37° C. for a minimum of 3 h. After the loading period, excess ⁸⁶Rb⁺ wasremoved and the cells were washed twice with label-free Dulbecco'sphosphate buffered saline (138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1mM Na₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH 7.4),taking care not to disturb the cells. Next, cells were exposed to either100 μM of test compound, 100 μM of nicotine, or buffer alone for 4 min.Following the exposure period, the supernatant containing the released⁸⁶Rb⁺ was removed and transferred to scintillation vials. Scintillationfluid was added and released radioactivity was measured by liquidscintillation counting

Within each assay, each point had 2 replicates, which were averaged. Theamount of ⁸⁶Rb⁺ release was compared to both a positive control (100 μMnicotine) and a negative control (buffer alone) to determine the percentrelease relative to that of L-nicotine.

When appropriate, dose-response curves of test compound were determined.The maximal activation for individual compounds (Emax) was determined asa percentage of the maximal activation induced by L-nicotine. Thecompound concentration resulting in half maximal activation (EC₅₀) ofspecific ion flux was also defined.

EXAMPLE 7 Determination of Binding at Non-Nicotinic Receptors MuscarinicM3 Subtype

The human clonal line TE671/RD, derived from an embryonalrhabdomyosarcoma (Stratton et al., Carcinogen 10: 899 (1989)), was usedto define binding to the muscarinic M3 receptor subtype. As evidencedthrough pharmacological (Bencherif et al., J. Pharmacol. Exp. Ther. 257:946 (1991) and Lukas, J. Pharmacol. Exp. Ther. 251: 175 (1989)),electrophysiological (Oswald et al., Neurosci. Lett. 96: 207 (1989)),and molecular biological studies (Luther et al., J. Neurosci. 9: 1082(1989)) these cells express muscle-like nicotinic receptors.

TE671/RD cells were maintained in proliferative growth phase accordingto routine protocols (Bencherif et al., Mol. Cell. Neurosci. 2: 52(1991) and Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946 (1991)).They were grown to confluency on 20-150 mm tissue culture treatedplates. The media was then removed and cells scraped using 80 mL of PBS(Dulbecco's Phosphate Buffered Saline, 138 mM NaCl, 2.67 mM KCl, 1.47 mMKH₂PO₄, 8.1 mM Na₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH7.4) and then centrifuged at 1000 rpm for 10 min. The supernatant wasthen suctioned off and the pellet(s) stored at −20° C. until use.

On the day of the assay, the pellets were thawed, re-suspended with PBSand centrifuged at 18,000×g for 20 min, then re-suspended in PBS to afinal concentration of approximately 4 mg protein/mL and homogenized byPolytron. Protein was determined by the method of Lowry et al., J. Biol.Chem. 193: 265 (1951), using bovine serum albumin as the standard.

The binding of [³H]QNB was measured using a modification of the methodsof Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946 (1991). [³H]QNB(Specific Activity=30-60 Ci/mmol) was obtained from NEN ResearchProducts. The binding of [³H]QNB was measured using a 3 h incubation at4° C. Incubations were conducted in 48-well micro-titre plates andcontained about 400 μg of protein per well in a final incubation volumeof 300 μL. The incubation buffer was PBS and the final concentration of[³H]QNB was 1 nM. The binding reaction was terminated by filtration ofthe protein containing bound ligand onto glass fiber filters (GF/B,Brandel) using a Brandel Tissue Harvester at 4° C. Filters werepre-soaked in de-ionized water containing 0.33% polyethyleneimine toreduce non-specific binding. Each filter was washed with ice-cold buffer(3×1 mL). Non-specific binding was determined by inclusion of 10 μMnon-radioactive atropine in selected wells.

The inhibition of [³H]QNB binding by test compounds was determined byincluding seven different concentrations of the test compound inselected wells. Each concentration was replicated in triplicate. IC₅₀values were estimated as the concentration of compound that inhibited 50percent of specific [³H]QNB binding. Inhibition constants (Ki values),reported in nM, were calculated from the IC₅₀ values using the method ofCheng et al., Biochem. Pharmacol. 22: 3099 (1973).

EXAMPLE 8 Determination of Activity at the α7 nAChR Subtype

Selective α7 agonists can be found using a functional assay on FLIPR(see, for example, PCT WO 00/73431 A2, the contents of which are herebyincorporated by reference), which is a commercially available highthroughput assay (Molecular Devices Corporation, Sunnyvale, Calif.).FLIPR is designed to read the fluorescent signal from each well of a 96or 384 well plate as fast as twice a second for up to 30 minutes. Thisassay can be used to accurately measure the functional pharmacology ofα7 nAChR and 5HT₃R subtypes. Cell lines that express functional forms ofthe α7 nAChR subtype using the α7/5-HT₃ channel as the drug targetand/or cell lines that express functional 5-HT₃ are used to conduct theassay. In both cases, the ligand-gated ion channels are expressed inSH-EP1 cells. Both ion channels can produce a robust signal in the FLIPRassay. Using the FLIPR assay, the compounds described herein can beevaluated for their ability to function as agonists, partial agonists orantagonists at the α7 nAChR subtype.

EXAMPLE 9 Summary of Biological Activity

Compounds 1-34 competitively inhibited the binding of radiolabeled MLAto rat brain hippocampus α7 nAChR subtypes with an equilibrium constant(Ki) values of 0.5-60 nM, indicating that they have very high affinityfor the α7 nAChR subtype. High-throughput screening indicated that noneof the compounds bound to α4β2 nAChR subtypes with any significantaffinity (Ki values >10 μM).

Compounds I-34 exhibited little or no agonist activity in functionalmodels bearing muscle-type receptors (α1β1γδ subtype in human TE671/RDclonal cells), or ganglion-type receptors (α3β4 subtype in the Shootersubclone of rat pheochromocytoma PC12 cells and in human SHSY-5Y clonalcells), generating only 1-12% (human muscle), 1-19% (rat ganglion) and1-15% (human ganglion) of nicotine's response at these subtypes. Thesedata indicate selectivity for CNS over PNS nAChRs. Because similarcompounds had been described by others as exhibiting muscarinic activity(see, for instance, U.S. Pat. No. 5,712,270 to Sabb and PCTs WO 02/00652and WO 02/051841), representative compounds (#s 1, 2, 4, 9 and 11) wereevaluated for their ability to inhibit [³H]QNB binding at muscarinicsites in the human clonal line TE671/RD. None of the compounds was ableto inhibit [³H]QNB binding, indicating that these compounds do not bindto human M3 receptors. Thus, compounds of the present invention aredistinguished in their in vitro pharmacology from reference compounds(see, for instance, U.S. Pat. No. 5,712,270 to Sabb and PCTs WO 02/00652and WO 02/051841) by virtue of the inclusion, in their structure, of the3-pyridinylmethyl substituent in the 2 position of the 1-azabicycle.

Following up on this intriguing finding, a comparison of α7 nAChRbinding affinities was undertaken, to determine the effect of the2-(3-pyridinyl)methyl substituent. The results are shown in Table 5. Itis clear from the data that inclusion of the 2-(3-pyridinyl)-C₁₋₄alkyl,preferably 2-(3-pyridinyl)methyl, substituent in the structuresubstantially increases binding affinity. Thus, compounds of the presentinvention exhibit both greater affinity at and greater selectivity forα7 nAChR subtypes than those compounds which lack the2-(3-pyridinyl)alkyl, preferably 2-(3-pyridinyl)methyl, substituent.

TABLE 5 a7 Ki Structure (nM)

120

40

53

7

5

9

The data show that the compounds of the present invention are potent α7nicotinic ligands that selectively bind at α7 nAChR subtypes. Incontrast, the compounds of the present invention do not bind well atthose subtypes of the nAChR that are characteristic of the peripheralnervous system or at M3 muscarinic receptors. Thus, the compounds of thepresent invention possess therapeutic potential in treating centralnervous system disorders without producing side effects associated withinteraction with the peripheral nervous system. The affinity of theseligands for α7 nAChR subtypes is tolerant of a wide variety of aryl (Arin Formula 1) groups and substituents thereon. Furthermore, thesynthesis is straightforward, efficient and amenable to massivelyparallel protocols.

Having disclosed the subject matter of the present invention, it shouldbe apparent that many modifications, substitutions and variations of thepresent invention are possible in light thereof. It is to be understoodthat the present invention can be practiced other than as specificallydescribed. Such modifications, substitutions and variations are intendedto be within the scope of the present application.

1. A method for the treatment of attention deficit disorder comprisingadministering a therapeutically effective amount of (R,R; R,S; S,R; andS,S)-N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof.
 2. The method of claim 1,wherein the attention deficit disorder is predominantly combined type.3. The method of claim 1, wherein the attention deficit disorder ispredominantly inattentive type.
 4. The method of claim 1, wherein theattention deficit disorder is predominantly hyperactive-impulsive type.